Small Scale Soapmaking - A Guidebook for Making your own Soap (original) (raw)

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  MlCFlOFlCHE REFERENCE LIBRARY A project ofVolunteers in Asia Small-S& Soapmakim Handbook By: Peter Donkor Publishedby: IntermediateTechnoFogyPublications 103/l 05 Scuthampton Row London WCIB 4HH U.K. In associationwith: Technology Consultancy Centre University of Science and Technology Kumasi GHANA Available from: IntermediateTechnology Publications 103/l 05 Southampton Row London WCIB 4HH U.K. Sma Reproducedwith permission. Reproduction of this microfichedocument in any form is subject to the same restrictions as those of the original document.
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  SnKALL-SCALE SOAPMAKING A handbook PeterDonkor Technology Consultancy Centre, llniversity of Science and Technology, Kumasi, Ghana in association with IT Publications 1986
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  ~-__ Intermediate Technology PublicationsLtd., 103-105Southampton Row, London WClB 4HH, UK. @ TCC and Intermediate Technology Publications 1986. Reprinted 1989 ISBN 0 94668837 0 Printed by the Russell PressLtd., Bertrand Russell House, Gamble Street, Nottingham NG7 4ET, UK.
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  Contents PREFACE ACKNOWLEDGEMENTS CHAPTER 1:INTRODUCTION 1.1 BriefHistory of Soapmaking 1.1.1 The Developmentof Soapmakingin Europe 1 1.2 The Developmentof Soapmakingin Ghana 1.1.3 Lqe-scale SoapProduction in Ghana 1.1.4 The Roie of ResearchInstitutions in Ghana 1.2 Definition andPropertiesof Soap 1.3 Hydrolysis of Soap 1.4 Detergent Action CHAPTER 2: RAW MATERIALS FOR SOAPMAKING 2-l FatsandOils 2.1.1 Classificationof FatsandOils 2.1.2 Brief Chemistryof FatsandOils 2.1.3 CommonOils Usedin Ghanafor Soapmaking 2.2 Alkalis 2.2.1 CausticSoda 2.2.2 Description of Processfor Local Production 2.2.3 CausticPotash 2.2.4 Description of Processfor LocalProduction 2.3 Other rawmaterials V Page ix xi 1 1 1 2 3 3 4 4 5 6 6 4 7 10 13 13 14 17 18 19
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  CHAPTER 3: THECHOICE OF SUITABLE OILS AND FATS FOR SOAPMAKING 3.1 SaponificationValue 3.2 Iodine Number 3.3 INS Factor 3.3.1 PrticticalApplication of INS Factor 3.4 Lathering andSolubility Propertiesof Soap CHAPTER 4: PLANT AND EQUIPMENT FOR SOAPMAKING 4.1 Equipment andPlantfor Laundry Soapmaking 4.1.1 SoapBoiling Tanks 4.1.2 CausticSodaStorageTanks 4.1.3 SoapMoulding Boxes 4.1.4 SoapCutting Tables 4.f .5 SoapStampingMachines 4.2 Equipment andPlantfor Toilet Soapmaking 4.2.1 Mixing Machines 4.2.2 Milling Machines 4.2.3 Plodders 4.3 Other Equipment andTools CHAPTER 5: PRE-TREATMENT OF FATS AND OILS FOR SOAPMaKING 5.1 Refining of Oils andFats 51.1 Alkali Refining 5.1.2 Another Clarification Method 5.1.3 Bleachingof Oils andFats CHAPTER 6: THE PROCESSOF SOAPMAKING 6.1 6.1.1 6.2 6.2.1 6.2.2 6.2.3 6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.4 Semi-boilingProcess Processingmethod Full-boiling Process SaponificationProcess Graining Out ClearBoiling andFitting Treatment of SettledSoaps Liquoring Filling Framing Drying andStamping Cold Process vi 21 21 23 23 24 26 27 27 27 29 29 29 31 31 31 32 33 34 36 36 36 37 38 40 40 40 42 43 44 45 45 46 46 47 47 , 49
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  CHAPTER 7: SMALL-SCALEPRODUCTION OF TOILET SOAP 7.1 Cold Process 7.2 Milled Toilet Soapmaking 7.2.1 Drying of SoapBase 7.2.2 Mixing of PerfumeandDye 7.2.3 Milling ‘7.2.4 Compressing 7.25 Cutting andStamping 7.3 RemeltedSoaps CHAPTER 8: NON-EDIBLE OILS FOR SOAPMAKING 8.1 NeemOil 8.1-l Soapmakingproperties 8.2 CastorOil 8.2.1 SoapmakingProperties 8.3 PhysicOil 8.3.f SoapmakingProperties 8.4 Processof Soapmaking CHAPTER 9: GHANA STANDARDS SPECIFICATIONS FOR SOAPS 9.1 Filled Hard SoapSpecifications 9.2 GenuineHard SoapSpecifications 9.3 Filled Carbolic SoapSpecifications 9.4 Toilet SoapSpecifications 9.5 MedicatedSoapSpecifications 9.6 PackagingandMarking of Soaps APPENDIX 1:Sometypical formulations for soaps APPENDIX 2: Properties of soapsfrom different oils/fats 52 52 53 53 53 54 54 54 54 55 55 57 58 59 59 59 61 63 63 64 64 44 65 45 67 70 vii
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  Preface In April andMay 1985,I visited Ghana to gather data for a book on the work of the Technology Consultancy Centre at Kumasi’s University of Science and Technology. TCC was founded in 1972,in an effort to adapt and transfer to ordinary Ghanaians some of the knowledge that is often held captive within university walls. It wassoon discovered,however, that the development of appropriate technologieswasnot the same thing asthe transfer of technology, and it becameclearthat the Centre would have to involve itself not only in projects that were relevant to the cultural and economicenvironment of the community, it would have to become involved in the community itself. This, in turn, led to an appreciation that even a basic technology like soapmaking cannot be compartmentalized. Thus, making soap became a bit like pulling a thread on a shirt: if you pull long enough, you will find that it is connectedto half the universe. Making soapin the context of Ghana’sprotracted economic difficulties meantnot only the developmentof asimplemethod that could meetrural conditions, but one that could survivethe temperament of the wildly fluctuating market place as well. When caustic soda, an essential ingredient, became unavailable,TCC devizeda techniqueand equipment for local manufacture.The traditional method of extracting oil from the palm fruit is laborious and expensive,and soin order to reduce costsand the burden on the women who do the work, TCC developeda low-costoil press,the production of which is now firmly establishedin severalsmallworkshopsin Kumasi. When ix
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  , palm oil becameaimosttotally unavailable during the drought and the economiccrisis of 1983,TCC begana searchfor non- edible oil substitutes, conducting successfulexperiments with both neem and castoroil. Perfume wasdevelopedfrom lemon grass. A measure rf the successof such experiments is the recent adoption of some of TCC’s techniquesand findings by the large iever Brothers soapplant in Accra. Peter Donkor’s book modestly avoidsdiscussionof the great pains that he and others put into the development of the technology he describes, and of the successthat has been achievedin having the processadopted on a widespreadscale in Ghana, by small urban and rural entrepreneurs, by village co-operatives and by development organizations. A further measureof successhasbeenthe number of requestsfrom other countries in Africa for assistancein establishing the process. Peter Donkor has travelled to Guinea Bissau. Mali, Togo, Sierra Leone and Mozambique to help set up small soapmakingenterprises. Weis therefore uniquely equipped to write about a processwhich ha,sbeentried and tested,not only in the sterile laboratories of the Ghana StandardsBoard, but in the bustling shopsand stalls of the Ghanaian market place. Ian Smillie London, 1986
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  Acknowledgements There is nodoubt about the fact that a lot of people have contributed in one way or another to the successof this book. My specialthanks go to Dr. J.W. Powell, Director of TCC, whose encouragementand editing aswell ascontact with the Intermediate Technology Publications madethe publication of this book possible. My sincere thanks also go to the Intermediate Technology Development Group in the UK, for funding the printing of the first edition of this book. I will alsolike to expressmy heartfelt thanks to the following people and companies: Miss Esther Akom and her assistants Miss Grace Dery and Angelina Pamford, all of TCC, who typed the draft of this book, Mr. W.A. Osekre, the University photographer who printed some of the pictures used in the book, the ObegamSoapEnterprise, Kumasi, and Kwamotech Ltd, Kwamo, who allowed somepicturesof their workshopsto be taken for this book. Last and not the least, my special gratitude goes to Mr. Smillie who agreed to write the preface of this book. Mr. Smillie paid a visit to TCC (when this book wasbeingwritten) to write up a comprehensive report on the activities of the Centre. Note Further information about equipment such asthat mentioned in Chapter 4 can be obtained by writing to the Technology Consuitancy Centre, Kumasi, Ghana. xi
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  Chapter 1 Introduction 1.1 BriefHistory of Soapmaking The need for soap, a cleansingagent, hasbeen felt ever since man became aware of the necessityto clean his body and environment in the primitive ages.Soaphastherefore acquired the status of a basic necessityin the modern civilized world. Soapmakingis one of the oldest industries in the world; most authorities claim that it originated on the sacrificial altars of early primitive people, when fat from animals killed on altars dripped over wood ashes,thereby combining with the potash in the ashesto form crude soap. 1.1.1 The Development of Soapmalcing in Europe It is recorded that the Gauls were the first to producesoapby mixing goat fat (tallow) with potash from beechwoodashes, and were followed by the Romanswho learnt the art after the conquestof the Gauls, under Julius Caesar.Soapmanufacture seemedto flourish in the eighth century in Spainand Italy, and wasintroduced in Francesome500yearslater, when factories wereestablishedin Marseillesfor soapmanufacturefrom olive oil. In the fourteenth and fifteenth centuries, soap was manufactured on a commercial scale in Italy in the city of Savona,and the words “savon”, “sabon” and “jabon”, which are French, Portuguese and Spanish words respectively for soap, are derived from the name of the city. The first record of soapmakingin England is in 1552,and from this time to the beginning of the 19th century, manufacture of soapdeveloped very slowly, being carried on essentiallyby the rule-of-thumb method. In 1787andthe years that followed, a major breakthrough was made in soap
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  production as aresult of two discoveries. Nicholas Leblanc discovered a processfor the chemical production of caustic sodafrom common salt in 1787,and a few yearslater Michael Eugene Chevreul carried out a successfulresearch into the constitution of fats and oils, and demonstrated that soapmaking was a chemical process involving the initial splitting of fatty acids and glycerol. These findings gave the soapmaker an unlimited supply of one of his basic raw materials - causticsoda. They also placed the soap industry on a scientific basisas soapmakerswere now in a position to know the nature of the chemical reaction involved in soapmaking. The history of many modern soapmaking companies in England can be traced back to the eighteenth and nineteenth centuries, although their growth at the time washamperedby high taxation. However, following the scientific breakthrough, soaptaxation wasabolishedin England, resulting in the riseof the demand and supply for soap. During this period, W.G. Lever became a dominating figure in the soap trade in England. In 1884, he introduced sunlight soap for the first time. Gradually, other soap manufacturers begandeveloping different kinds of soapfor cleaningdifferent articles, and more attention was also given to the form in which the soap was presented. Lux flakes, for example, were first marketed in 1900,and were a big success.Lever also introduced the useof tropical vegetablefatsand oils like palm oil, coconutoil, palm kernel oil, etc, for the making of soap at a time when the traditional sourcesof animal fats for soapmakingwere running behind demand in England. 1.12 The Development af Ssapmaking in Ghana Soapmakingwasan indigenoustechnology in the country long before the arrival of the Portuguesein 1482,especiallyamong the Fanti tribe who were making soapfrom crude palm oil and potashfrom wood ashes.Though this potashsoapis still being made and used in the rural areas of Ghana, very little improvement has been made on the processingmethod to produce a good quality soap acceptable to the urban soap consumers.Probably the rural population still enjoysthe useof this soap for bathing purposes becauseof its good cosmetic properties. Though the soap is very soft and usually black or 2
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  ashcolour, it isvery mild and hassomebleachingproperty on the skin, which has made the use of the soap very popular amongwomenwho prefer to be fair in complexion. Apart from its bleaching property, it is also used for dermatological purposes.Its use in the treatment for ringworm, and prickle heat rashesis well known. The sort of nature of potash soap, and its short-shelf life coupledwith the difficulty in the preparation of causticpotash (prepared from the ashesof cocoapods, plaintain peels, etcj and/or the scarcity of potash at the local market, has limited the production of this soapto someextent. It wasno surprise that when the country was colonized the indigenous soapmakersswiftly switched over from the production of the traditional soapto the laundry soapintroduced by the colonial masters, which involved the use of ready-made imported causticsoda. 1.1.3 Large-scale Soap Production in Ghana Sincethe first Portuguesesteppedon the shoresof the land, laundry soapmakinghassteadily been carried out on a small scaleby local soapmakersalong with the dwindling volume of potassiumsoap production. In 1963,Lever Brothers set up a soap complex in Tema to start large-scale production of laundry, toilet and powder soapsto boost the local production of soap. More recently, two other soapcomplexeshavebeen establishedin Kumasi and Cape Coast. l.I.4 The Role of Research Institutions in Ghana One interesting situation with the local prc,duction of soapin the country is that very little attempt has been made to improve on the quality of soapproduced. It is unfortunate that up till n#Jwall sorts of low quality soapspopularly known as ‘Don’t touch me’, becauseof their high caustic sodacontent and slippery nature, are produced in the country. Although someresearchprogrammeshavebeencarried out to improve the quality of soap by the researchinstitutions, their findings have not benefited the small-scale traditional soapmakerswho produce both the laundry and potash soaps. The biggest attempt yet made was by the Technology ConsultancyCentre (TCC) which in 1983set up a pilot soap plant to conduct researchon the improvement of local soaps 3
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  and to offerfree training to local soapmakers on the technology of good quality soap production. The Centre still offers this training and produces soapmaking equipment for saleto local soapmakers. The Centre’s current soap training programme is geared towardsthe production of laundry soapbut someattempts are also being made to improve the colour and hardnessof the traditional potashsoap. 1.2 Definition of Properties The definition of soap is generally restricted to the combination of fatty acids and alkalis obtained by reacting variousanimal andvegetablefats and oils with causticsodaor potash, the former giving hard soapand the latter soft soap. Both soaps are readily soluble in hot water or alcohol. However, they dissolve very slowly in cold water forming a turbid solution owing to slight decomposition. Sodium soaps (made from caustic soda) are found to be insoluble in very strong caustic solutions, and for the most part in strong solutions of brine; hence the addition of strong solutions of brine to a solution of sodium soapcausesthe soapto separate out and rise to the surfaceof the causticor salt so!ution. This separation(alsoreferred to as‘graining’) of soapisemployedin commercial soapproduction. On the other hand, addition of brine to a solution of potassium(potash)soapmerely resultsin double decomposition giving rise to sodium soap and potassiumchloride. Thus C17H3sCOOK+ NACl = Cl7 HD5COONa + KC1 i.e. (Potassium Soap) + (Common Salt) = (Sodium Soap) + (PotassiumChloride) The solubility of different soaps in brine varies very considerably. 1.3 Hydrolysis of Soap When soap is treated with cold water it is said to undergo hydrolysis- the breakingdown of the soapinto its component parts. The hydrolysis results in the liberation of an acid salt. The reaction can be representedin its simplest form by the equation: 4
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  2 Cl7 Hs5COONa-t Hz0 = N&X-I + HNa (C,7H35COO), (Soap)+(Water)=(Caustic Soda)+(Acid Salt) 1.4 Detergent Action Many theories have been proposed to explain the detergent action of soap- the property possessedby soap to remove dirt. However, the commonest explanation is that the alkali liberated in the processof hydrolysisattacksanygreasymatter on the surface being cleam=d, and as fat is dissolved, the particles of dirt are loosenedand easily washedoff. Another theory suggeststhat the alkali set free by the hydrolysis of soap serves as a lubricant, making dirt less adhesive,and thus promoting its removal. Yet another theory statesthat the alkali tends to lower the surface tension of the water, and thus permits the emulsification of fat-bearingdirt particles on the surfaceof the material being cleansed. 5
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  Chapter 2 Raw Materialsfor Soapmaking The raw materialsfor the makingof soapcoverawide rangeof substances which may be classified under the following headings: I. Fat and oils 2. Alkalis 3. Filling agents 4. Water 5. Salt h. Perfumes 7. Colours or dyes However. fats and oils constitute approximately 00% of the soapmaker’sraw materials. and ;I dctaiicd treatment of fats and oils is made in this chapter. 2.1 Fats and Oils The cost of production and properties of any particular soap are largely dependent on the nature and properties of the various oils and fats used in its manufacture. Thus it is very important for the soapmakcr to be f’ulty conversantwith the physical, chemical and soapmakingpropcrtics of thc oils and fats being used. Since no two oils have identical soapmaking properties, the art of soapmakinglies not only in the boiling operation but in the judicious selection of the oils and fats to produce the qualities needed. 2. I .I. Classification of Fats and Oils Fats and oils are esters of fatty acids and glycerol. The distinction between fats and oils is purely an arbitrary one, basedon their physical state at ordinary temperatures- the 6
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  oils being liquidand the fats solid or pasty. Fats and oils are divided into three classes,namely, fixed oils, mineral oils and essentialoils. However, fixed oils form the main raw materialsfor soapmakingasthey decomposeinto fatty acids and glycerol when strongly heated, and are easily saponified by alkali. Fixed oils and fats, which include both animal and vegetable fats and oils, are further classified accordingto their physical properties as follows: a) Nut oils: These oils are characterized by a large proportion of fatty acidswith low molecular weight, especialy lauric acid. Examples of these oils are coconut oil and palm kernel oil. These oils (especially cuconut oil),when used in toilet soapsare the chief suds-producingingredients. They saponify easily with strong alkali solution (30-35”Be). Oncetheseoils begin to saponify the processproceedsrapidly with the evolution of heat. They alsorequire largequantities of strong brine (1648”Be) to grain their soaps,and the grained soapstend to carry more salt than other soaps.Theseoils are more suitable for the making of cold processsoaps. b) Hard Fats: The hard fats contain appreciablequantities of palmatic and stearicacids.Examplesof thesefats are palm oil, animaltallow andhydrogenatedoils. Theseoils or fatsproduce slow-lathering soapsbut the lather produced is more stable over long periods of time than the nut oils. In soapmaking, they are first saponified with weak alkali (10~lS”B@),and in the final stageswith stronger alkali solutions. c) Soft Oils: These oils have substantial amounts of unsaturatedacids, namely olcic, linoleic and linoleneic acids. The soapmakingproperties of theseoils vary with their fatty acid composition, and the physicaland chemical properties of the acids.Examplesof theseoils are groundnut, castor,cotton seed,fishoil andolive oil. Theseoils cannot producehard soap when used alone for soapmaking. They arc usually blended with nut oils. Their soaps,however, lather freely andhavevery good detergent properties. 2.1.2 Brief Chemistry of Fats and Oils Soapmakinginvolvesa definite chemicaldecompositionof fats and oils into their constituent parts, namely fatty acids and glycerol. The fatty acidscombine with causticsoda, potash or other baseto form soap, and the glycerol remainsfree. 7
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  All fats andoils usedin soapmakingconsistof a mixture of compoundsof glycerol with fatty acid which occur in nature in the form of triglycerides.The mostimportant of theseacidsfrom the soapmaker’spoint of view are stearin, palmitin, olein and laurin. The presenceof stearin and palmitin, which are solids at room temperature, gives firmness to fats and oils. The greaterthe percentagepresentthe harder the oil or fat, and the higher its melting point. Where olein, which is liquid at ordinary temperature, is the chief constituent, the oil or fat is soft. The soapmaking properties of fats and oils can be determined by the molecular weightsof their fatty acids.With increasingmolecular weight in the caseof naturally occurring saturatedfatty acidsin fat or oil, the following properties are found: 1. The boiling point of the oil rises, 2. The melting point of the oil/fat rises, 3. The saponification value of the oil/fat decreases. Also, the properties of their corresponding sodium soaps vary asfollows with increasingmolecular weight: 1. The solubility increases, 2. The lathering properties improve up to lauric acid and deteriorate from lauric aoid upwards, Plate 2: Palm kernels
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  3. The stabilityof the lather increases, 4. The detergent action decreases, 5. The soapshave milder skin action asthe seriesprogresses, 6. The property of holding filling solutions such as sodium silicate decreases. This explains the reason why nut oil (such as coconut oil) soapslather readily and profusely but not stably. They also have a firm texture and are hard but dissolvemore readily in water than do soapsfrom the hard oils. They can alsoretain a good amount of water, and take up fairly !arge quantities of fillers like sodium carbonate. Naturally occurring saturated fatty acids (The C,Hz,Oz Scrica) No. of Melting clmn1on ClJrboni- Chefk.wl ~Molix+rrlar Point Name SiJtbtJS F0~~rltllU Weight (“C) Orcws In Butyric 4 cg-i,COOH 88.1 -8 Milk fat Caproic 6 CSH1,COOH 116.16 - 2 Milk fat Caprylic 8 CTH &OOH 144.21 16.0 Milk fat Capric 10 C,H ,&OOH 172.26 31.3 Coconut Laurie 12 C, ,H$OOH 200.31 43.6 Coconut My&tic 14 CllHz&‘OOH 228.37 54.0 Animal fat Palmitic 16 W-hCOOH 256.42 63.0 Animal/ vcgctablc fat Stcaric 1x C,7H3SC00H 284.47 69.6 Animaii vcgctablc fiat Arachidic 20 C,pHa>COOH 312.52 75.3 Groundnut Behcnic 22 G, HJJCOOH 340.57 80.0 Groundnut Lignoccric 24 C?jHJ7COOH 396.67 85.87 Bccsw;lx 2.13 Common Oils used in Ghana for Soapmaking Various oils and fats have become established in Ghana for scapmaking.Theseare all edible oils, although someattempts havebeencarried out by the TCC to identify local non-edible oils assubstitutesfor edible oils for soapmaking. Theseoils which areextracted locally usingboth commercial andtraditional technologiesinclude palm oil, coconutoil. palm kernel oil, sheabutter and cotton seedoil. 1. Pc?lm Oil Palm oil is extracted locally ::t”the commercial level using 10
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  hydraulic presses, andat the small-scale level using hand- operated screw presses.’ However, traditional extraction techniquescater for about 30% of the total palm oil produced in the country. The oil forms about 5040% of the total oils and fats usedin Ghana for soapmaking. Palm oil usually producesa crumbling soapwhich canot be readily milled for toilet soap production, but with 20-25% coconut oil blend, it producessatisfactorytoilet soap. ii. Coconut oil The oil is producedfrom copra mostly in the WesternRegion, by the Esiamavegetableoil mill, usingoil expellers.However, traditional extraction methodsare usedwidely in the Western Region and other areas of southern Ghana. The oil is extensively usedto blend other oils like sheabutter, palm oil and cotton seedoil for soapmakingbecauseof its property to produce hard and lathering soaps.It also finds application in the production of liquid soaps becauseits potassium soap remainsclear at low temperatures. Becauseof its high saponification number, it requires a strongcausticsolution (known aslye) for its saponification. Its soap is usually white, firm and soluble with rapid forming lather which is not very stable. iii. Palm Kernel Oil This oil is produced mostly in Ghana using traditional techniquesand is usedinterchangeablywith coconutoil in both ‘laundry and traditional potassium soapmaking. Its soap has similar properties to coconut oil soap. iv. Shea Butter Sheabutter is a fat which is extracted in the northern part of Ghana, where shea trees are found, using only traditional extraction techniques. The fat is somewhattough and sticky, and the amount of unsaponifiable matter present is considerable. The fat produces soap of soft consistency with oily appearanceand thus needsto be blendedwith coconutor palm kernel oil to improve the hardnessand lathering properties. Ii I. This technology was developed and promoted by the TCC. A full account o: !he technology can be found in the TCC report ‘The Dcvclopment of Apprcp&!e Technology hand screw press for the extraction of palm oil’ by Peter Donkor. 12 c
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  is the chieffat usedin the north for soapmaking,sincemost of the other oils mentioned are not found in the north. v. Gutton Seed Oil Cotton seedoil is not widely produced in Ghana. The Crystal Oil Company in Accra is the main producer of cotton seedoil soapstock for soapmaking. The crudeoil saponifieswith easebet the soapis difficult to grain. It producessoapof soft consistency,if usedalone, and hasa bad odour. 2.2 fiudis The two alkalis popularly used in the making of soaps are causticsodaand causticpotash. 26.1 Caustic Soda Commercial causticsodais creamy in appearanceand fibrous in structure. It readily absorbsmoistureandcarbonicacid from the air to form sodium carbonate. Due to its hygroscopic property of absorbingmoisture, it must not be exposedto the air. Caustic soda is also very corrosive to the skin and aluminium containers, and assuchmust be handledwith great care. It is available on the market in various forms, namely flakes, powder, sticks and blocks. The powder and the flakes are very convenientto handle but are costlier than the solid or block causticsoda,and are normally usedwhen the volume of soapproduction is very small. For largesoapproduction units, however, it is more economical to buy solid caustic soda in drums. To removethe causticfrom the drum, the drum is first pounded on all sideswith a heavy iron hammer, causingthe causticsodato crack. The crackedcausticis then chiselledand broken into piecesand dissolvedin the right amount of water to obtain the concentration needed. Gommercial Prvduction Commercially. causticsoda is pvlduced by the electrolysis of brine (sea water), the byproduct of such a process being chlorine which is usedfor bleachingand water treatment. The descriptionof the processinvolved in causticsodamanufacture is beyond the scope of this book and will therefore not be discussed. 13
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  P1.ATE 3: Usinghydrometer to &ermine the strength of causticsoda sohrtion. Lanrl Production (Using Precipito tiorr Rextim) In Ghana. the Technology ConsusltancyCentre (TCC) of the University of Scienceand Technology (UST), Kumasi, has developed a technology for the local production of caustic soda.The technologywhich wasdesignedto produce 1OOkgof causticsodaof about 8Okgin 9-W% solution and 2Okgin 5% solution has generated a lot of interest amongst small-scale soapmakers,and the governmentwhich is currently promoting the technologyamongthe membersof the GhanaSoapmakers’ Association. 2.2.2 Description of process for local production Raw mnteri& The raw materials required for the making of the causticsoda are: a) sodiumcarbonate- an imported raw material bought from 14
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  ICI (Ghana) Ltd.,Tema, or the open market in 50kgbags; b) slakedlime - aby-product of the manufactureof acetylene from calcium carbide and water by L’Air Liquide. Presently,the lime is awastematerial for the company,and is collected by soapmakersfree of charge. Eqru’pment: The equipment for the manufacture of the chemical is a cylindrical tank reactor (Plate 5) made from galvanized steel sheetwith a diameter and heigh; of 120cm(4ft). The reactor is equippedwith four baffleswhich extendfrom top to bottom at 90” to the walls of the tank. Their purpose is to promote a good agitation of the slaked lime suspension during the reaction. .Anagitator, axially positioned in the tank, consistsof a shaft and a 4-bladedaxial flow turbine which is 1705cm(7in) above the bottom of the reactor. The width of each blade is 4cm(Min), the length is 1605cm(&42in), andthe pitch of the bladeis45”.Theshaftof the agitator isdirectly rotated by a lhp electricmotor at arotational speedof 950rpm.The agitator and the baffleshave beendesignedto keep the lime in suspension during the reaction. 45cm(18in) from the bottom of the tank.,along the walls of the reactor is a swivelling decantingpipe with 31.25mm(1Xin) valve through which the clear solution of caustic soda is decanted, and at rhe centre of the bottom of the reactor is a 1Ocm (4in) valve through which the sludge of calcium carbonate(a byproduct of the reaction) dischargedafter rinsing with water. The reactor can be wood fired, or ell five domestic heating elements each designedproduction capacityper day is and has a design reaction temperature time of three hours. Pl-OCt??SS and unreactedlime is ectrically heated with of 2kW rating. The 1OOkgof causticsoda, of 90°C and reaction Nine hundred litres of water is measuredinto the reactor and heated to a temperature of 92-95°C. Using the heating elements,this temperature is attained after about eight hours’ heating, but with strong firewood, it takes only about three hours. When the temperature is reached, the agitator is 15
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  switched on, and150kgof sodium carbonate introduced into the water for absolute dissolution. When the carbonate is completely dissolved 182kgof dry slaked lime is introduced into the reactor, and the reaction allowed to take place for three hours to completion with continuous agitation. After three hours, the heating is stopped and the calcium carbonate suspensionis then allowed to settle after which the clear solution of causticsodais decanted.The solution hasa caustic concentration of 103g/litre and sodium carbonate concentration (i.e. unreacted carbonate) of 2lg/litre. When usedfor soapmaking, this carbonate goes into the soap as a filler. 2.2.3 Caustic Potash Causticpotash possesseschemical propcrtics similar to those of caustic soda. It is, however, much stronger in chemical reaction than soda. It producessoap of soft consistencyand higher solubility in water than sodium soaps,and is therefore generaily used for the making of liquid soaps,shampoosand soft soaps. Commercial Production Commercial production of caustic potash involves the same two methodsasalready describedin the production of caustic soda, namely precipitation reaction method and the electrolysismethod. In the precipitation reaction, slaked lime is reacted with potassium carbonate, while in the electrolysis method the electrolyte usedis potassiumchloride. Loc+?lProduction In Ghana, caustic potash is produced on a small scale by traditional soapmakersfrom a numberof vegetableashes.The processis describedas follows: Raw Materials Cocoa pods, spent palm bunches, plantain or banana peels. kapok tree wood. Equipments Basketor earthenwarepot, jute bag or straw, tray or bucket, wide and shallow pan to crystallize causticsolution. 17
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  2.2.4 Description ofProcess for Local Production The processinvolves burning any one of the raw materials mentioned above into white ashes.It must be noted that the raw material must be very dry before being burnt at high temperature to ensure complete combustion and the production of fine white ashes.A kiln hasbeendesignedby the Engineering Faculty of the University of Science and Technology (UST) for the production of white ashes.Someof thesekilns are being usedin the southernpart of Ghanafor the production of white ashesfor causticpotash manufacture. After burning the raw material, a given volume of the ashes is measuredinto a big basket lined with a cleanjute bag, and placedon a drum by meansof two horizontal rods. The ashes are moulded up around the sides of the basket to leave a depressionin thecentreto ensureproper draining of the caustic solution. An earthenware pot with a small hole made at the bottom can be usedasa substitute for the basket. A quantity of warm water (about twice the volume of the ashesput in the basket) is slowly added to the ashes,allowing 18
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  the ashesto absorbas much water as possiblebefore adding more water. After the asheshave absorbed enough water, brown lye (causticpotashsolution) beginsto drop slowly from the bottom of the basket into the tray or drum under it? as more water is put on the ashes.The dripping must be sEow enoughto allow maximum dissolution of the causticpotashin the ashesin the water put in the basket. When no more solution drops, the lye obtained is put back in the basket to repeat the leachingprocess.This secondleachingincreasesthe strength of the lye. A suitable strength for soapmakingcan be checkedcrudely by dipping a chicken feather or putting a fresh egg into the solution. A stronger solution will dissolve the feather, or support an egg. A hydrometer can also be usedto determine the density of the solution, if available. If the solution is found to be weak,boiling will concentratethe solution to the required strength. 2.3 Other Raw Materials In addition to fats, oils and alkalis, a lot of other chemicalsare used in comparatively small quantities to give various characteristics to soaps. These chemicals include builders, fillers and various other additives. Builders Building agentsare essentiallyusedto ‘build up’, i.e. increase the detergent power of soaps.Their usein soapshasenabled the soap industry to face, to some degree, the severe competition from synthetic detergents. Sodium carbonate, sodium silicate and sodium sulphate are alkali builders commonly usedin soapmaking. Fillers Fillers are usedto add weight to the soapwithout in any way addingto the detergentproperty of the soap.They increasethe bulk of the soap, and hencereduceproduction cost. They are not, however, usedin good quality genuinesoaps. A number of filling agentsare usedasfillers, but the most popular onesare clay, kaolin, talc, starch, common salt, chalk and magnesiumcarbonate. Soda ash and sodium silicate are also usedin large quantities asfillers - sodium silicntc when 19
• 30.
  used,alsoactsasan antioxidant toprotect the soapfrom going rancid. It alsoimprovesthe smoothness,binding, transparency and hardnessof the soap. In the use of fillers, care must be taken for their selectionand quality astoo much may dampen the washingproperties and keeping quality of the soap. commonsalt Brine (a saturated solution of salt) is very important in soap manufacture.It is neededto grain out the soapin a full boiled process,in order to separateout glycerin and excesscaustic from the genuinesoap.Salt usedin graining hasto bepure, i.e. free from compounds of iron (Fe), calcium (Ca) and magnesium(Mg), otherwise they will causethe deterioration of the soap and introduce impurity in the form of their insoluble soaps. Colours Colour is added to soap to make it more attractive, and sometimesto maskthe original colour of the product. Oil and water soluble dyesare suitable for soapcolouring. Perfumes Someoils and fats produce soapsof unpleasantodour (even if they are well clarified before use)which needto be perfumed. However, in the useof theseperfumes,considerationmust be givento the action of the particular perfumeon the soap.Some synthetic perfumes and essential oils cause soap to darken rapidly on keeping, e.g. clove oil, and vanillin, while others decomposethe soap. Lemon grassoil, citronella oil, oil of lavender(French) and bergamot oil are suitable oils. Perfumesareaddedto soapsat low temperaturesasthey are very volatile at high temperatures. 20
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  Chapter 3 The Choiceof Suitable Oils and Fats for Soapmaking Whether soapproduction is done on a small or large scale,the quality and properties of the soapto be produced dependto a large extent on the type of oil used; hence the choice of a suitable oil is very necessaryfor the production of good soap. Many small-scalesoapmakersin Ghanaseemto be ignorant of this important fact, and therefore produce soaps of poor quality. Though a lot of technical and economic facters determine the choice of oil by the soapmaker,e.g. availability of the particular oil needed, and the type of equipment and machinery as well as the processof manufacture being used, certain specific constants of the oil or fat determine the hardness,lathering properties and w&ing efficiency of the soap to bc produced. Knowlcdgc of these constants. if used properly. is a big assetto the boapmakcr.They help to forecast the quality of soap to be cxpcctcd from the choice of a particular oil or blend of oils used. The mostimportant of theseconstantsarethe Saponification Value. Iodine Number. the INS Factor and the Solubility Ratio (SR). This chapter briefly dcscribcsthe meaningof these constantsand their applications to soapmaking. 1. Saponification Value This very important constant helps to determine the quantity of caustic soda or potash required to neutraiizc (saponify) a given quantity of oil or fat chosenfor the making of soap. It is defined asthe quantity of causticpotash (in milligrams) required to saponify Ig of oil or fat. Saponification valuesarc always expressedin terms of caustic potash. Thcrcforc the 21
• 32.
  value if givenmust always be multiplied by a factor (O-7)to obtain its value in terms of causticsoda. Let us seethe practical useof this value in soapmaking,by assumingthat asoapmakerhas3kgof palm oil for soapmaking, and he is told that the saponification value of the oil is 202. How can he estimate the quantity of causticsoda required to saponify the oil? This can be worked out asfollows: If the saponification valueof the oil is 202,then the quantity of causticsodarequired to saponify lg of the oil is 202x0.7mg (ie 202~0*7~10 g). Hence the quantity of caustic soda required to saponify 3OOOg(3kg) of the oil will be 202x0-7x10~3x3000g, or 424*2g. Thus from the given saponification value, the soapmaker knows that he requires 424gof causticsodato processthe 3kg of oil into soap. Saponification Value and Iwline Numbers for Some Common Soapmaking Oils and Fats Oil/ Fur Palm Oil Coconut Oil Palm Kernel Oil Shea Butter Catton Seed Oil Animal Tallow Vegetable Tallow Lard Nccm Groundnut Sunflower Castor Supponigicntion V&w” 200-20s 251-264 248 178-189 193-195 190-199 192-195 195 186-204 186-194 189-194 181 hhre mrmber 49-59 8-10 1l-15 56-65 108-I 10 35-46 40 59-63 69.0 90- I03 126 84.1 These values represent the number of milligrams (mg) of 100% caustic potash requited to saponify lg of the oil. In order to calculate the amount of caustic s<)dil required we must compare the rclativc molecular weight of caustic soda (40) and caustic potash (Sh). . . Caustic soda required = # x saponification vnluc/g of oil = 0.7 X saponification value/g of oil Let us consider this second example by assuming that a soapmakerhasabicnd of oil consistingof 1kg of palm kernel oil and 3kg of palm oil for soapmaking, given that thz saponification values of the kernel and palm oils are respectively 248 and 202. Let us determine the quantity of causticsodarequired to saponify the 1kg (1OOOg)of kernel oil. 22
• 33.
  Sinceit has asaponfication value of 248, the quantity of soda required will be 2%8~0~7~1O-~~lOOOg,i.e. 1736g. That for the 3kg palm oil is found to be 424-28. Therefore 538g of causticsodawil?be neededto saponifyanoil blend of 3kgpalm oil and 1kg palm kernel oil. It mustbe noted, however, that the saponificationvalueis of significancewhile making soap using the cold or semi-boiling process, but in the full boiling process it is of little or no significancesinceany strength of causticsoda solution can be usedandgrained. The averagesaponification valuefor most of the soapmakingoils (excluding the nut oils) is 190. 3.2 Iodine Number This constantis defined asthe number of centigramsof iodine absorbed by lg sample of the oil. The number, in fact, indicatesthe presenceof unsaturatedacidsin the oil or fat. The higher the number for an oil, the greater the percentageof theseacids,and thus the softer the soapproducedfrom the oil. The soft oils (like cotton seedoil and groundnut oil) havehigh iodine numbers and are readily oxidized. The iodine number thus indicatesthe hardnessof the soap,the lower the number, the harder the soap produced. Cotton seedoil has an iodine number of 109while coconut oil has an iodine number of 9. This explains why coconut oil produceshard soaps. The useof this number in determining the hardnessof soap produced from a blend of oils is not very reliable sinceit does not giveany information on the natureof the unsaturatedacids in the blend. The saponification value,on the other hand, gives directly the molecular weights of the fatty acids in the blend, and thus indicates the presence of lower molecular weight saturatedacids. In view of this it is very advisableto make use of the two constants in the selection of the suitable oil for a particular soap to be produced. This gives rise to another factor known as the INS (Iodine Number Saponification) factor. 3.3 INS Factor This factor is expressedas the difference between the iodine number and the saponification valueof the oil or fat. It is used to predict the quality of soap to be obtained from a blend of 23
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  - INS Factors ofCommon Oils and Fats wed in Soapmaking Name of OillFat INS Factor Coconut Oil 250 Palm Kernel Oil 235 Vcgctablc tallow (mafura ) 165 Mutton tallow 155 Beef tallow 150 Palm Oil 146 Lard I37 Olive Oil 108 Cotton Seed Oil 85 Soya Bean Oil 54 Linseed Oil I5 3.3.1 Practical Application of INS Factor According to the Ghana standards for soap?a good soap should have the following physical properties: 1. good colour, bright in appearance, and free from objectionable odour; oils. This factor rangesfrom 15to 250for soapmakingoils and fats. The liquid oils with high proportions of unsaturatedfatty acidshavelow factors while the hard fats and nut oils with low molecular weight saturated acidshave high factors. Generally, with increasing INS factor, the following observationsare found: 1. the oils vary from liquid to solid and produce harder soap; 2. the detergent and lathering properties as well as the solubility of the soap decreases(except the nut oils) with improved colour, and capability to hold more filling agents; 3. the soap or oil diminishes in its tendency to go rancid on ageing. 2. be of medium hard consistency,and producefree and stable lather over long periods of time. The abovestandardsindicate that oils with extreme high and low INS factors are both unsuitable for use alone to make soap, asthe nut oils with high factors will produce too hard a soapand the soft oils with lower factors will produce too soft a soap. The hard oils with medium factors (e.g. palm oil and tallow) will be the best. They, however, produce soapsof low lathering power, and must therefore be blended with soluble and quick lathering oils or fit with lower INS factors. These 24
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  -1oils on theother hand havethe dual purposeof increasingthe lathering properties of the soap aswell assoftening the soap, the degreeof softening dependingon the quantity usedfor the blend. It is therefore necessaryto increase the hardnessby addinga certain proportion of a nut oil (e.g. coconut oil) to the blend. This will further increasethe lathering properties of the soap.Therefore a good oil blend must be madeup of a nut oil (coconut oil), soft oil (ground nut oil) and hard oil (palm oil). It is interesting to note that the nut oils are unique oils for blendssincethey havethe property of increasingboth hardness andsolubility of soapswhile all other oils capableof hardening soap(e.g. tallow, palm oil) have the disadvantageof reducing solubility. The question now confronting the soapmaker is: what quantities of these three oils (soft oil, hard oil and nut oil) should be suitable for a good oil blend to produce the required quality of soap? Let us considerhow the INS factor can be usedpractically to resolvethis issue. Let usassumethat a soapmakerhasto make a blend of palm oil, coconutoil andcotton seedoil suchthat the blend will have an INS factor of 146(which correspondsto that of palm oil and lies in the INS rangefor soapoils) and constitute 50% of palm oil. We therefore needto determine the percentagesof cotton seed oil (say, X) and coconut oil (50-X) which must be added to the palm oil to form the blend. Using the INS factors of the oils, we add up these factors according to their percentagespresent in the blend, and the sum should be equal to the INS factor of the blend, i.e. 146. Therefore, for palm oil: & x (146) for coconutoil w x 250and for cotton seedoil w . . . jjj (146) + +$&(50-X) + w = 146 i.e. X = 31.5 and (50-X) = 18.5 Thus the blend shouldconsistof 50% palm oil, 3105%cotton seedoil and 18~5%coconut oil The above calculations may seema little cumbersometo a 25
• 36.
  lot of localsoapmakersbut if followed carefully they help the soapmakerto form a suitable blend, with the quantities of oils at his disposal, sincea blend of the salve INS factor produces soapof the samehardnessirrespectiveof the component parts of the blend. Lathering and Solability Properties of Soap The lathering and solubility properties of soap is found to be dependenton the INS factor of the oil or oil blend usedin the making of the soap. Oils and fat with an INS of 130-160are individually unsuitable for soapmaking on account of low lathering. Though the low INS factor oils reducesthe hardness of soap, they tend to increasethe solubilitv, but the rate of softening is greater than the rate of solubility increase.Thus the presenceof coconut or palm kernel oil (high INS oils) in thesesoapsare essentialsincethey havemarked effect on both hardnessand solubility. However, the following observations must be noted as the useof someof theseoils is subject to limitations: a) Palm kernel oil, which serves as a good substitute for coconutoil in soapmaking,should not be usedin toilet soaps asthe odour of the oil is likely to develop in the soapwith time. Also any oils with high levelsof unsaturatedfatty acids (cotton seedoil) are not suitable for toilet soapmakingon the grounds of rancidity. b)Generally, any quality of tallow, and bleachedpalm oil can be used to make household laundry soaps, where colour playsan important role. Among the soft oils, cotton seedoil is most preferable for a blend, but sunflower and soyabean oils are the best substitutesfor cotton seedoil. c) It is worth noting that, although current choice of an oil or fat is very important, it is only a necessarybut not a sufficient condition in good soapmaking. Improper processingtechniquesduring the soapsaponification process will produce a low quality soap in spite of the choice of suitable oils. 26
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  Chapter 4 Plant andEquipment for Soapmaking Plant and equipment required for small-scalesoapproduction units vary in designfrom one placeto another. Generally, they include soap-boiling pans for soap boiling, wooden or metal soap frames to hold liquid soap for solidification, a cutting table to cut solid soapblocksinto slabs,barsand tablets, a foot or hand operated stamping machine, hydrometers to measure the strengthof causticsodaandcommonsalt solutions. Caustic soda mixing tanks, and other items like rubber gloves, weighing scales, buckets, and polythene sheets for frame lining. 4.1 Equipment and Plant for Laundry Soapmaking 4.1.1 Soap-boiling Tanks These pans may vary in size and material depending on the maximum volume of soapto be boiled and the processbeing used,but they are normally made of mild steel or castiron or galvanizedmaterials of suitable gauge.Generally, the pan has a cylindrical body with a truncated conical base(to effect easy drainage of the hot soap), and a drainage pipe fitted to the bottom of the pan. A typical wood-fired boiling tank designedby the TCC and popularly usedin Ghana by small-scalesoapmakersis madeof 16gaugegalvanizedsteel in the form of a cylinder measuring 12lcm in diameter and 90cm in height welded to a truncated conical baseof 30cmhigh and 30cmin bottom diameter (Plate 7). The total volume of the boiling tank is 1600litres and it is capable of boiling half a tonne of soap per batch. At the bottom of the tank is a 3cm hole fitted with a 3cm galvanized 27
• 38.
• 39.
  steelpipe with amatchinggatevalve through which the boiled soapis dischargedinto the soapframes. The tank is mounted on a one metre high ring frame support, made of 2Scm iron rod, surroundedby burnt bricks and clay with an entranceand a chimney to form a hearth for firewood heating. In some developing countries like India, the wood-fired boiling tanks are gradually being replaced by tanks equipped with closedand open coils through which steamat about 45psi flows (from a boiler) for the boiling of the soap. In the rural areasof Ghana, soapmakingat the village level is done using a 200litre oil drum for the boiling of the soap. 4.1.2 Caustic Soda Storage Tanks This is a tank in which caustic soda solution of the required strengthis preparedandstored for usewhen needed.The tank may be rectangular or cylindrical in shape, but made of a strong and thick material to withstand attack from caustic soda. 4.1.3 Soap Moulding Boxes Theseare wooden or metal framesinto which the boiled soap is run for cooling. The boxesare rectangularin shapeand the number of boxesusedby a soapmakerdependson the volume of soapnormally producedin the unit. The sidesof the frames can be made to be taken apart for easyremoval of the dried soap, or can be permanently nailed. If the latter is used polythene sheetsare used to line the box before the boiled soapis run into them. A wooden soap moulding box designedto give 52 bars of soap of 3*7X6x37cm in dimensions will measure 20X4x96cm inside with a wall thicknessof 2cm. 4.1.4 Soap Cutting Tables After the soapis hardenedand taken from the soapmoulding box, it isin the form of asolid rectangularblock which needsto beslabbedand further cut into barsor tabletsasrequired. This isdoneusinga cutting table (Plate 8). The wooden table isfour or six legged, with a crossbar running width-wise acrossits central line, and boards 9cm high running length-wise along eachside. On one sideof the table along the crossbar are two or three suspensionwires kept taut by a butterfly nut on top of the crossbar. The gap between any two wires is arranged to 29
• 40.
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  give the dimensionsofthe soapslabwhen cut. Similar setsof suspensionwires are arrangedon the other sideof the table to cut the slabsinto barsor tablets. The soap block is cut into slabs by manually pushing the block againstthe suspensionwires. 4.1.5 Stamping Machines To give a commercial finish to the cut soaptablet, the soapis moulded into a preciseshapeand an inscription or trademark of the manufacturer put on one or both surfacesof the soap usinga stampingmachine.The foot or handoperated machine has a vertical treadle motion and gives a direct blow to the soap.Two dies are normally required for both surfacesof the soapare stamped.The diesare madeof hard brassfor a better finish. The bottom die normally rests in the box which holds the soapwhile the top die is fixed to the plunger. To stampthe tablet, it is put in the soapholder and the hand or foot lever operated. The two dies, with the trademark engravingson them, move vertically in opposite directions againstthe soap, which is thus stamped on both sides. The stamped soap is automatically releasedon the return stroke. 4.2 Plant and Equipment for Small-scale Toilet Soapmaking The preparation of toilet soapon asmall-scaleinvolvesvarious operations of soap base preparation, chipping of soap base, mixing of chips with perfume and colour, milling of soapinto flakes, compressingof milled soap, and cutting and stamping of compressedsoap. Equipment required for the preparation of the soap base, cutting and stamping of soap tablets is the same as already describedunder Section4.1. However the mixing, milling and compressionoperations require the following equipment. 4.2.1 Mixing Machines This is alsocalled an amalgamatorand is usedto mix the dry soapbase(in the form of chips), perfume, colour andanyother additive. The unit consistsof a hopper fixed on a mixing drum provided with a tilting arrangementfor easyunloading of the mixed material (Plate 9). The mixing is done by a sweepof bladesmade of stainlesssteel. The Indian model designedfor 31
• 42.
  - use by villageand cottage soap industries has a material handling capacity of 20kgIhour. Plate 9: Mixing machine 4.2.2 Milling Machines The object of milling is to render the soapmore homogeneous. The milling machineconsistsof a hopper sitting on a chamber of three or four granite rollers fitted with a suitable gearing system(Plate 10). The rollers are connectedin sucha manner that they rotate at different speeds, thus increasing the efficiencyof the milling process,andensuringthat the action of the rollers is one of rubbing rather than crushing. By meansof 32
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  suitably arranged screws,thepressureof the rollers on one another can be adjusted to give the issuingsoap ribbons any required thickness. - Plate IO: Milling machine 4.2.3 Plodders The plodder, alsocalledanextruder, is acompressingmachine which compressesand binds the milled soap ribbons into a solid bar suitable for cutting and stamping. It consistsof a hopper set onto a strong metal conical-shapedcannon-like tube which taperstowardsthe nozzle, and in which a singleor twin screwis moving andpropelling the soapto the conicalend (Plate 11). When the soap is fed into the compression chamber, it is forced through a perforated metallic disc, and subjectedto high pressureto be compressed.The soapfinally 33
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  L emergesthrough the nozzleto which an attached cutter of suitable shapecuts the extruding polished and neat soap bar into the required length. The nozzle is equipped with a cartridge electric heater providing temperatures between 50- 55°C to allow the soap to be easily forced out. The temperature is automatically controlled through a thermostat provided at the top of the heating chamber to avoid the soap becomingblistered if the nozzleis too hot, or being of poor and dull appearanceif the temperature is low. The Indian model has a material handling capacity of 20kg/hour. Phte II: Plodder 4.3 Other Equipment and Tools Apart from the plants and equipments described in this Chapter. certain useful items are also required in the general art of soapmaking. These items include a weighing scalefor weighing raw materials; rubber gloves and boots to prevent 34
• 45.
  bodily contact withcaustic soda* solutions; enamelled, galvanizedor plastic bucketsor containersto hold causticsoda solution, water and oil; a plastic sheet for lining the soap moulding box; and a stirrer if stirring soap is to be done manually during the boiling process. 35
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  Chapter 5 Pre-Treatment ofFats and Oils for Soapmaking In Chaper 3 the raw materials required for the making of soap were discussed.Notable among these materials are fats and oils. Depending on the characteristicsof the fats or oils they may be subjected to various pre-treatments like clarifying, bleachinganddeodorizing. The sort of treatment to be applied dependson theoil type andits purity, aswell asthe type of soap to be produced with the oil. 5.1 Refining of Oils and Fats Oil refining comprisesvarious processesof clarification of oils and fats to rid them of impurities and free fatty acids, and any unwanted odour, and the bleaching of the oil to remove objectionable colour. 5.1.1 Alkali Refining Irrespective of the processusedin the extraction of oils, the crude oii may contain certain amounts of objectionable impurities which may consistof pulp, andother componentsof the oil seedsor nuts in suspension.Also, during periods of storage and handling of the oil seeds, slight decomposition (gradual breakdown of the glycerides) of the oils in the seeds usually occursgiving rise to the presenceof free fatty acidsin the oils, the extent of the decomposition depending on the length of storage of seeds.The presenceof free fatty acids, water and other impurities are chiefly responsible for the rancidity of oils, thus making saponification of the oil very difficult. One of the common methodsusedin the refining of oils and fats is by the useof weak causticsolution, referred to asalkali 36
• 47.
  refining. During theprocess,the free fatty acidsin the oil react with the weak causticsodasolution to form soapstock which also absorbssomecolour, odour and impurities from the oil, thus rendering the oil clean. It is always advisable to determine, as a first step in the refining process,the content of free fatty acidsin the oil sample (by titrating the oil with standard alkali) to enable the soapmakerto calculatethe amount of causticsodarequired for the refining. For example, if it is found that the free fatty acids presentin an oil sampleis 0=6%,then 1OOkgof the oil contains 006kgof free fatty acids to be neutralized. A 20”Be solution (of relative density l* 16) of caustic soda is normally used for refining. Sucha solution contains 14*3%of pure causticsoda. It is also known that 14% (by weight of fatty acid) of pure caustic soda is required to neutralize a given weight of fatty acid. Thus O*bxO*14kg,or 0=084kgof 100% caustic soda will be required to refine 1OOkgof the oil. Using a 20”Be solution (of 14.3% strength) 0@$4/0*143or 0059kgof the solution will be required to refine 1OOkgof the oil. In practice, however, Osl- 005%more solution is used. The processof alkali refining involves heating the oil in a suitable tank to around 32°C and while stirring the correct quantity of 20”Be caustic solution is evenly sprinkled on the surface.After severalminutes of the addition of the solution, brownish or dark clots, which are saponified acids and gelatinousimpurities, will be formed in the oil while it is being stirred. The oil is then heated to 50°C and the stirring stopped. It is then allowed to cool overnight, after which the refined oil is siphoned through a swinging draw-off pipe. 5.1.2 Another Clarification Method A simple method of clarifying oil at small-scaleand cottage soapindustries in Ghana involves boiling the oil or fat in half its volume of water for 4-6 hours. Somescentingmaterials like lemon grass,cinnamon leaves,orangepeels,etc, are addedto the boiling oil. During the boiling processthe steamfrom the oil-water mixture takes along with it some of the undesirable odour of the oil while the scentingmaterials give some scent (deodorize) to the oil. After the boiling, the fire is put out and the mixture allowed to cool. The cleanclarified oil which floats 37
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  on the topof the water is then siphoned from the tank while the water with the settled impurities from the oil is drained off from the bottom of the tank. 6.1.3 Bleaching of Oils and Fats Three bleaching methods are generally employed in the bleaching of oils and fats, namely earth bleaching, air bleaching and chemical bleaching. Earth Bleaching In this processthe clarified oil to be bleachedis heatedto 90- lOO”C, and 4% of Fuller’s Earth and a small quantity of activatedcharcoal are added to the oil and slowly agitated for 15-20minutes to keep the bleach in suspension.The oil and bleachare then filtered in a filter press,or the oil is allowed to cool for a night and decanted,whenthe bleachingagentssettle down to the bottom of the tank. Air Bleaching This process is widely used in rural soapmaking for the bleaching of palm oil. In this process, clarified palm oil is heated to 200-250°Cin an open tank for 4-6 hours depending on the quantity of oil treated. In the courseof the heating the oil is oxidized and the red colour of the oil soon vanishes.In some caseswhere the bleaching is done in a steam jacketed tank with an open (perforated) coil, air is blown continuously through the oil by meansof the coil when the oil is heated to 1OO*c. Chemical Bleaching This processis generally usedfor the bleachingof palm oil and other deepcolour oils like cotton seedoil and mustardoil. The method, which is referred to as the bichromate method, involves dissolving potassium bichromate in hot water and addingthe solution obtained to the clarified cleanoil heatedto 52°C. Dilute sulphuric acid is then run into the oil and stirred well. The bright red colour of the oil gradually changesinto a green colour, and after some minutes of agitation, the oil is allowed to cool and the green chrome liquor at the bottom of the tank on which the bleachedoil floats is drained off. The oil is then washed (without further heating) with hot water containing somecommon salt to removeany tracesof chrome liquor left. For every tonne of oil IO-12kg of potassium 38
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  ----Ibichromate and 20-27kgofdilute sulphuric acid is used. Care must be taken so that the bleaching temperature of 52°C of the oil is not exceeded or else the resultant oil on saponification will yield a soapof reddish-brown colour. 39
• 50.
  Chapter 6 The Processesof Soapmaking Various attempts have been made to produce soap by first decomposingthe fat or oil into fatty acids and glycerin, and then converting the acidsinto soapby treatment with sodium or potassium carbonate. However, three conventional methodsof soapmakingare generally usedin both large- and small-scale soap production units. These methods include semi-boiling, full-boiling and cold processes, and will be discussedin this chapter. 6.1 Semi-boiling Process The process,although not suitable for the production of toilet soaps,canbe usedto producelaundry and all typesof soft and liquid soaps.The processdoesnot permit the removalof waste lye which contains the glycerin produced in the soapmaking process,and hencethe glycerin, which tends to decreasethe hardening property of the soap but improves the cosmetic property, isretainedin the finished soap.However, the method hassomeadvantageoverthe other two sincelargequantitiesof good soapcanbe producedwithin a short time. The useof the method also allows a high percentage of fillers to be incorporated in soaps,thus increasingthe soapbulk. In Ghana about70%of the laundry soapandall the traditional potassium soapsproducedby the small-scaleproducersemploy the semi- boiling process. 6.1.1 Processing Method The soft and hard oils or their blendsare very suitable for this processwhich involves melting the oil or fat and running a weak 9-10% causticsodasolution into the oil, and boiling the mixture. In all 14-15%of the weight of the oil is the quantity of 40
• 51.
  caustic soda requiredfor the saponification of the oil. This weight of caustic soda is dissolved in ten times its weight of water to obtain a9% solution. When the causticsolution is run into the oil, saponification starts when an emulsion is formed as the soap is stirred. More causticsolution is then run in to prevent the massthickening. After sufficient solution is added bit by bit to complete the saponification, boiling of the mass continues until the soapis clear. During the boiling processmoderate heat is maintained and eachaddition of causticsodasolution must be allowed to react with the oil before the next addition is made. A hastyaddition of the lye in the initial stagesof the processmay retard the saponification, or at the final stagesof the saponification may result in the graining of the soap,while judicious addition will keep the massin a form of smooth homogeneousemulsion. If the soap shows any signs of separation or graining, further water or oil is addedto bring the massto a homogeneousstate. Plrrte 12: Weighing cnustic so&a with n spring balance 41
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  The end ofthe processis easily recognizedby an experienced soapmaker. However, crude tests can be made to determine when saponification is completed. The ‘ribbon test’ involves taking a small sampleof the soapfrom the pan and cooling it. When a little quantity of the cooled soap is pressedbetween the thumb andforefinger, the soapshouldcomeout in the form of firm shiny ribbons with slight opaque ends and be clear when held againstthe light. If the cooled sampledrawsout in threads, there is an excesswater present in the soap, and further boiling is required to evaporate more water. If the opaque ends appear and vanish, the soap is oily and requires more caustic, while if the soap is grainy, or turbid and somewhatwhite, it indicates a high level of unreactedcaustic, and requires more oil. A physical test - the taste test - can also be done to determine the level of caustic. This test involvescooling a small quantity of the soap, and tasting with the tip of the tongue. A very sharp bite indicates too much causticin the soap,while no bite at all indicatesa high level of unsaponifiedfat or oil. A good soapshould give a faint bite on the tongue. After the completion of the boiling process, the fire is withdrawn, andthe soapallowed to cool in the boiling panwith occasionalstirring. At this point, perfume and colour can be stirred into the soap,if required, andthe final soappoured into soapmoulding boxes.It is then allowed to stayfor 24-36hours to harden, after which the moulds are emptied and the solid soapblock cut into the required sizesand stamped. 6.2 Full-boiling Process The process, popularly used by large and some small soap industries is the most important commercial method of soapmaking. It involves the treatment of fats or oils with an appropriate amount of alkali andremovalof wastelye from the soapat the end of the process.The processproduceshard and firm soaps,though it takes a longer time than the semi-boiling process,and is mostly usedfor the production of laundry soap and soapbasesfor toilet soaps. The processconsistsof four stages,namely saponification of the oil with alkali, graining out of the soap.boiling on strength (or clear boiling) and fitting. 42
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  Phte 13: Soap-boilingruing a KC-designed boiling tank capable of producing 500 bars of soap a day 6.2.1 Saponification Process The processis started by putting the melted oil into the boiling tank andrunning aweak (9.10%) causticsodasolution into the oil. The mixture is then boiled to start the saponification. The beginningof the saponification is denoted by the formation of an emulsion. When saponification hasstarted caustic sodaof higher strength (NoBe solution of relative density l-4) is frequently added in small quantities with continued boiling. Sometimesit provesdifficult to start the saponification and in suchcasesa small quantity of soapscrap may be added to induce the saponification. Rapid addition of caustic alkali in the initial stagescanalsoentirely delay saponification in which casewater should be added and the boiling continued till the excessalkali is taken up for the saponification to proceed.The endof saponification canbecrudely determined by the ‘ribbon’ and ‘taste’ tests already discussed in Section 6.1.1. When 43
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  saponification is completed,the soap becomesfirm and dry with a permanent faint caustic taste on the tongue when cooled. The soap, which now consists of imperfect soap together with water in which is dissolvedglycerin andanyslight excessof causticsoda, is then ready for graining out. 6.2.2 Graiuiug Out The object of this is to separate the waste lye (which is a mixture of glycerin produced during the soap boiling process andexcesscausticsodasolution) from the soap.This isbrought about by the useof common salt in the dry form or asbrine. The term ‘graining’ is usedhere becauseafter the introduction of the salt, the homogeneous soap has the appearance of grains. During the graining process,brine of relative density 1.2 is added to the boiling soapand boiling is continued. Too much brine must not be addedat a time. Usually the total salt usedis 840% by weight of the oil used,dependingon the type of oil. Lesssalt is required for tallow and palm oil while more salt is neededfor coconut and palm kernel oils. As the salt is added and the soap allowed to boil and stirred, the soap is gradually thrown out of the solution, and losesits transparent and homogeneousappearance,becoming opaque and grainy. The graining is comp!etewhen the soapis practically free from foam and floats asneatsoapon the lye. At this stage,a sample of soaptaken from the tank consistsof distinct grainsof soap and a liquid portion which will easily separate.The boiling is then stopped and the excesslye allowed to settle for several hours or overnight. It is necessaryto cover the boiling pan and allow slow settling of the lye over a longer period of time to give the soap massenoughtime to separateinto four layers, namely, a small bottom layer of brine with impurities, and excesslye, a second layer of soapcontaining some salt and water, a third layer of clean transparent soap (neat soap), and a top layer of a thin crust of soap. The bottom layer of brine is drained out while the secondand top layers can be removed and converted into bar soapby boiling with water. The third layer of neatgrainy soapiseither worked out with a trowel to break the grains to obtain homogeneoussoap, or boiled with a small quantity of water to bring it to a smooth homogeneous form and cooling after draining into soap 44
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  moulds. When thesoap is sufficiently cooled in the soap moulding box, it is taken from the mould, cut into the required sizesand stampedready for use. 6.2.3 Clear Boiling and Fitting The object of clear boiling and fitting is to obtain a pure soap suitable for the making of toilet soaps, by removing the last tracesof impurities from the grained soap. In the clear boiling, complete saponification is attained and the soap is hardened. During the process,the bottom layer of the soapis drained out after the graining. The content of the boiling tank is then boiled with strong caustic solution of 25-30"Bk (relative density 1.21to 1.26). More solution is added asit is absorbed until the soap is again grained, and is then allowed to boil steadily. As the boiling continues, complete saponification takesplace, andthe boiling is stopped. The grained soap is left for somehours to allow the settling of the excesslye which is then drained off. The soapis then boiled with a little water to make it smooth and homogeneous. This boiling process is called ‘fitting’. During the fitting operation, samples of the soap are taken from time to time to determine the quality of the soapand the end of the operation. If the soapis good, asmallquantity taken on a trowel shouldslip off from it without adheringto its sides. If the soap adheres, too much heat was used for the fitting, and a little lye must therefore be carefully added to the soap and boiled againuntil the desiredcondition is attained, andthe boiling stopped. After the fitting, the boiling pan is covered and allowed to stay for 2-6 days depending on the quality of soapin the pan. On complete settling, the content of the pan divides into four layersconsistingof a top layer of a thin crust of soap, a secondlayer of good settled soapcontaining about 6043% of total fatty matter (TFM), a third layer of darker soapwith TFM of about 30%, forming about 15-20% of soap in the pan, and a bottom layer of spent lye containing glycerin and which can be extracted. 6.3 Treatment of Settled Soaps After the soaphassettled into the four layersthe bottom layer of spent lye is drained off while the third and top layers are collected and converted into low grade soap by boiling. The 45
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  secondlayer of goodsoapisthendrainedinto anotherpan(i-e. cleansed) and treated to obtain the final product. In the cleansingprocess,careis taken to avoidthe presence of any of the low gradesoapforming the third layer. The temperature at which the soapis cleanseddepends on the soap type - soaps to be ‘liquored’ should not be cleansedtoo hot or separation will take place during the liquoring; a temperature of 66°Cis an ideal temperature for this. Cleansingtemperatures of ‘74 76°Care suitable for firm unliquored soaps. After the cleansing,the soap is stirred, or clutched, until a sufficiently low temperature is attained. 6.3.1 Liquoring This involves the addition of various alkali solutions to the cleansed soap to produce soaps of different qualities. Liquoring can be done during the stirring (clutching). Among the alkalis most frequently usedaresodiumsilicateandsodium carbonate.The latter may be usedin *iheform of sodacrystals containing 63% of water dissolved in its own water of crystallization on heating, and in that manner added, giving it firmnessand increasingits detergentproperties. It canalsobe addedto soapasasolution of sodaash,either concentrated(of relative density l-31) or of variousstrengths(of relative density l-125 upwards)at a temperature of 60°Cto stiffen and harden the soap. In the choice of the solutions, caremust be taken asstrong soda ash solution in firm soaps results in a brittle product, whereasthe texture of a weak soap will begreatly improved by suchaddition. It is advisableto havetest samples of sdutions in the soap to find out what proportions and strengths of sodium silicate or carbonatewill be bestsuited to the gradeof soapto beproduced. However, 1()0/nof thequantity of thesoap is preferable. 6.3.2 Filling This operation is done after the cleansingand clutching, or after the liquoring if the cleansedsoap is liquored. The filling agents,asalready describedin Section2.3 of Chapter 2 serve no usefulpurposeexceptthat of increasingthe bulk of the soap and henceadding weight to it. After choosingthe right filler, the required quantity is stirred into the soap. 46
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  Plate 14: Drainingsemi-boiled soap from the boiling tank to the modding box lined with polythene sheet 6.3.3 Framing Having cleansed,clutched, liquored and filled the soap, the soapmay be perfumed and drained into soapmouding boxes (frames) to solidify into blocks. The length of time the soap should be cooled is dependent on the quality and quantity of soapaswell asthe temperature of the surroundings.This time may vary from 3-7 days after which the soap blocks are removedfrom the frames, ready for cutting. 6.3.4 Drying and Stamping After the soap has been cut into the required bars using a cutting table, bar soapcanbe dried by stackingthe barsacross each other so that air has free accessto each bar for a day. They are then placed in storagebins for 2-3 weekswhen they will be in perfect condition for packaging and distribution. Heavily liquored soapsareunsuitablefor long periodsof drying treatment, as the bars may tend to lose water rapidly, 47
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  Plate 15: Removingsoap from the soap moulding box for cutting I 1 : 1 ; ‘.yf, .-v*i,; ,“, _ “2 (‘1b’;, ‘$:.q Plate 16: Soap clttting operation. The soap block is first cut into slabs before being cut into bars 48
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  Plate I?: Arrcrrtgirlgj%slred sorry bars ONshelv~~.sfor drying resulting in shrinkage and distortion. The dry soap is then stamped by means of a stamping machine. If necessary, the soap is transferred to racks after the stamping to expose it to air after which it is wrapped and put into cartons for the market. 6.4 Cold Process This process involves the treatment of fat or oil with a dcfinitc amount of alkali and no separation of waste lye. Although it is possible with great care to produce neutral soap by this process the soap is very liable to contain both free alkali and unsaponified fat. The process is based on the fact that the glycerolcs of certain low fatty acids oils (e.g. nut oils like) coconut and palm kernel oils) readily combine with strong caustic soda solutions at low temperatures, and generate sufficient heat to complete the saponification reaction. 49
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  Coconut oil isthe chief oil employed but sometimestallow, palm oil lard, cotton seedoil, or evencastoroil canbeblended with coconut or palm kernel oil to make the soap, with slight temperature changeto render the blend liquid. Soapsmade with theseblendsresemble,in appearance,milled toilet soaps. In this process,it is very necessaryto use high grade raw materials. Oils and fats should be free from excessacidity becausecausticsodarapidly neutralizesfree fatty acidsforming granules of soap which grain out in the presenceof strong causticsolution, andsincethe grainy soapis difficult to remove without heat increase, the soap tends to become thick and gritty and sometimesdiscolours. The caustic soda being used must also be pure, i.e. must contain as little carbonate as possible, and the water must be soft and all other materials carefully freed from particles of dirt. The processinvolves stirring into the milled fat or oil in a tank, half its weight of caustic soda solution of 40”B6 of (relative density l&37) at a temperature of 24°C for coconut and 38°C to 49°C for the blends. The running of the caustic solution into the oil must be done slowly and continuously. Whenthe solution is being run into the oil the mixture must be stirred in one direction. When all the causticsodasolution has beenrun into the oil and the mixture stirred for 30-45minutes, chemical reaction takes place with the generation of heat, finally resulting in the saponification of the oil. The content of the tank looks thin at first, but after somefew hoursit becomes a solid mass.The edgesof the soapbecomemore transparent as the process advances, and when the transparency has extended to the whole mass, the soap is ready, after perfuming to be poured into moulding boxes for hardening, cutting and stamping. A little causticpotashsolution usedto blend the causticsoda solution greatly improvesthe appearanceof the soap,making it smoother and milder. If filling agentsareto be incorporated in the soapthis isdone after the running in of the causticsolution. For laundry soaps, silicate of soda, talc and starch are chiefly used. Silicate solutions must be of strength 3O”rw. However, it is quite possibleto make a soap of 45-50% TFM without any filling agentbeing added, simply by using a weaker causticlye. 50
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  Some Advantages andDisadvantages of Cold Process over Bo!!ing Process Advantages Cold Process Hot Process i. Requires inexpensive equipment Equipment and capital investment and hence small capital can be very expensive. investment. ii. Less skilled labour. and simple processing technique. More skilled and experienced labour required. Processing technique more complex. iii. Glycerin produced during the Glycerin removed (except for semi- soap making process is retained boiling process). in the soap, preventing the cracking of the soap on keeping, and incrtzasing its emollient proper-tics. iv. Soap produced easily dissolves in The soap is not readily soluble water with abundant iathcr. except when certain pcrcentagcs of Soft oils ilrC uSCd. v. Soap has whiter colour, and hence the process is used to produce some special types of soap. Products soaps of varying colours. vi. The process is quicker and rcquircs incxptnsive perfumes for scenting. Bisacivan rages The process is long, sometimes taking weeks (full boiling) to complete. Cola Process i. Bad soaps produced cannot be reclaimed using the same process. ii. Soap normally contains slightly higher levels of free caustic alkali. iii. Only small yuimtitics of SOilp Cilll bc produced at a time. iv. Process produces soap of less purity as impurities in spent lye cannot be washed. 51 Hot Process Bad soaps produced can bc reclaimed using the same process. Process allows the production of ncutrid SOihpS. Lilrgc quimtitics of S(Jilp can bc produced ilt il time. Very pure soap can bc produced during graining process. .
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  Chapter 7 Small-scale Productionof Toilet Soaps By definition, a toilet soapis a soapspeciallyadaptedfor toilet usedue to its good detergent and lathering properties, aswell as its freedom from caustic alkali and any other ingredient likely to causeirritation to the skin. Toilet soapscan be classifiedaccordingto their method of manufactureinto the following classes: a) cold processsoap, b) milled soap, c) remelted soap. The processesfor the manufacturing of thesethree typesof soapsare describedbelow. 7.1 Cold Process In practice, good toilet soapsare produced using the milling method. However, on the small scale,some of the relatively cheapervarieties of toilet soapscan be made using the cold process. The manufacturing technique is almost the sameasalready describedin Section6.4. The p-- -aW~.SS consistsof melting the fat or oil in apanandsievingout anyimpurities in it, after settling. The oil is then run into the saponifying pan and cooled to 35°C.The right quantities of dye and perfume are then stirred into the oil. Dyestuff shouldbe dissolvedin a small quantity of water and filtered to avoid specksof colour in the soap. For carbolic varieties, the cresylicacid is not added until after the saponificationof the oil. After adding the dye and perfume to the oil the required quantity and strength (38-40”Be) of causticsodasolution is run into it in athin streamwith constant
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  stirring until theoil is completely saponified and the mass begins to thicken. Finally the thickened massis drained into soapmoulding boxesand allowed to harden slowly. The quantities of raw materials to be used depend on the type of soapto be produced. For simple white toilet soapsfor example, a blend of oils consisting of 20kg of coconut oil, 27.3kgof tallow (or palm oil) and 1l8kg of castoroif is treated with 25kg of 4O”Becausticsodasolution. 7.2 Milled Toilet Soapmaking Almost all the high class soaps used on the market pass through the milling process which consists briefly of the following operations: drying of soapbase,mixing of perfume and dye, milling, compressing,cutting and stamping. 7.2.1 Drying of Soap Base The final soapobtained after the treatment of the settled soap already describedin Section 6.3 servesasa soapbasefor the milled soap. After the solidification in soapframes, this soap contains28-30% of water, and this quantity hasto be reduced by half before any satisfactory milling can be done. Drying is bestdone by chipping the soapinto smaller sizesand exposing the chipsin trays to a current of hot air at 35-40°C.There are severalforms of drying chambersin which the chipsin the trays are placed upon a seriesof racks, one above the other and warm air circulated through. It is very important that the correct amount of moisture should be left in the soap, not too much or little - the exact point can be determined only by judgement and experience, and dependson the nature of the soap to be made and the quantity of perfume to be added. However, a rangeof ll-14% moisture gives good results. Below this range, the soap will crumble during the milling processand the finished soapwill have the tendency to crack, while above the range, the soap will stick to the rollers of the milling machine, and mill only with difficulty. 7.2.2 Mixing of Perfbme and Dye When the soap chips have been dried to attain the required water content, they are put into the amalgamator (the mixing machine) and the required amount of perfume and dye added 53
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  to mix thoroughlyat toom temperature. The quantity of perfume to be added varies considerably with the perfume type. For cheapgrade soapsO-6to l-7% (by weight of soap) are used, while for costly soaps 2-3% are sometimesused. 7.2.3 Milliug From the amalgamator, the soap is put into the milling machinefor the chipsto be milled into more homogeneousthin soapribbons. Prolongedmilling doesnot improve the quality of the soapbut only givesa semi-transparentappearanceto it. 7.2.4 Compressing This follows the milling process.The operation tends to bind the soap ribbons into a solid bar suitable for cutting and stamping. In this process, the milled soap is fed into the compressor(or plodder), and as the compressiontakes place the soap extrudes through the nozzle of the compressoras a long polished solid bar. 7.24 Cutting and Stamping In cutting the extruded soap into the required sizes for stamping, the cutter should shapeit somewhat similar to the required finished tablets. An ordinary cutting table can be employed. Stampingof the cut piecescan be done with either foot or hand operated stamping machines. 7.3 Remelted Soaps In this method of making low grade toilet soaps,a mixture of variouskinds of soapsis remelted in a boiling pan and stirred. The stirring or agitation should not be too vigorousor lengthy as this will causethe soap to become aerated. When all the soap is melted, addition of peal ash (potassium carbonate) solution is made to the soap to give it a firmer and smoother texture, render it more transparent and increaseits lathering properties. The required colour is then added in a soiuble form, and lastly the perfume. To give the desiredodour, large quantities of perfume need to be added; hence cheaper essentialoils should be used. I The perfumed soapis then drained into framesfor cooling, cutting and stamping. 54
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  Chapter 8 Non-edible Oilsfor Soapmaking Traditionally, soapmakingin Ghana and many other African countries involves the use of various types of edible oils and fats. However, over the years there has been a very rapid increase in the demand for edible oils and fats for both consumption and industrial purposes.This hasresulted in the increasein the price of such edible oils like palm, coconut, palm kernel and shea butter which are extensively used in Ghana for soapmaking. The large increase in the prices of edible oils has in turn rendered soapmaking relatively unprofitable. It hastherefore becomeimperative to searchfor other alternative sourcesof raw materialswhich could provide suitablesubstitutesfor the edible oils traditionally employedin soapmaking. In Ghana some researchon the use of non-edible oils for soapmaking, carried out by the Technology Consultancy Centre, hasidentified three locally available plants whoseoil seeds produce non-edible oils which can be used for the production of soap. These three are neem, castor and physic nut (Jatrupha). 8.1 Neem OiI Neem oil is obtained from the seedsof the neem tree. In Ghana, apart from the treesbeing planted in cities for shade, they are also cultivated on plantations by the Forestry Department for useasfirewood. Suchplantations are found in the Accra Plains, Achimota, Winneba, Navrongo, Yendi, Bawku, Cape Coast and Inchaban. The oil content of the local kernel is about 45%, and the oil is greenish yellow, non-drying with an acrid and bitter taste, 55
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  and an unpleasantgarlicodour. The oil is extensively usedto blend other oils in the making of both laundry and toilet soaps in India. Analysis of locally extracted oil gave the following properties. Physical Properties Colour Odour Taste Solubility Density Refractive Index Chemical Properties greenish yellow repulsive garlic very bitter insoluble in water 0.905gkC 1.47 Saponification Value 194.78 Iodine Value 65 Unsaponifiable matter 2.5% 8.1 .l Soapmaking Properties The oil saponifies readily and gives a hard-grained soapwith good and very stable lather. When usedalone for the making of soap it is very necessaryto grain the soap as this helps to remove most of the disagreeableodour and colour. On the other hand, if it is used to make soap with other oils, it is advisableto first make neemoil soap.After the soaphasbeen grained, the other oils are stirred into the soap and the required amount of caustic soda solution added to start the saponification again. Neem oil soap is used for both laundry and antiseptic purposes. Below is the analytical results of neem oil soap made from local neemoil. Analysis of Neem Oil Soap Slightly garlic Garlic Much lather and Much lather and stable over long stable over long periods periods hard hard high high 70.4% 60% 0.0% 0. I % 20.1% 25.2% 57 Odour Lather stability Hardness Washing Efficiency Total Fatty Matter Free Caustic Alkali Moisture
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  Castor oil isobtained from the seeds of the castor plant (Abonkruma in Fanti). In Ghana, the oil has no economic value asno oil is extracted from the seeds.Apart from using the plant to give shadeto young seedlingsof oil palm, cocoa, coffee and coconut at nurseriesof the Ministry of Agriculture, the plants are normally seen growing wild, especially at the outskirts of towns andvillagesin both savannaandforestzones of Ghana. Plate 19: Castor plant The seedcontains4555% of oil which can be usedto blend other oils for soapmaking. Below are the properties of locally extracted castor oil. Physicd Properties Colour - Odoirr Light yellow or colourlcss - acrid Taste - Relative density nauseating - 0.93 Chernicnl Properties Saponification Vahic lodinc Value 184 83.6 58
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  Soapmaking Properties Castor oilconsists mainly of ricinoeic acid and smaller percentagesof stearicand palmitic acids.The oil hasthe same behaviour as coconut oil as regards to saponification, being readily saponified with strong caustic lye. The oil produces hard, white, and transparent soap. Below are the analyzed properties of soapmade from locally extracted castor oil. Property Colour Hardness Lather stability Washing efficiency Total fatty matter Free caustic alkali Moisture s Analysis result of soap (Hot process) pale very hard much lather but very unstable - lather vanishes after few seconds low 67% 0.0% 20.5% 8.3 Physic Oil The physicoil is obtained from the seedsof the physic nut (or Jatropha) plant, locally calledAduadze in Fanti or Nktandua in Twi. The plant is often grown for hedges and fences but commonly found growing wild around the Afram plains, central region around Cape Coast, and the Axim area. The seedcontainsabout 52% oil. The oil hasbeenusedalong with plantain ashesfor the making of home-madesoapsin Ghanain the olden days.However, its usein the production of soaphas been forgotten in recent times. Locally, the oil has been found to have the following properties: Colour Colourless Relative Density 0.91 Refractive Index 1.47 Saponification Value - Iodine Value 78.3 8.3.1 Soapmaking Properties Physic oil soap is relatively soft but produces a lot of very stablelather over long period of time. To increaseits hardness the oil can be blended with IO-20% of castor oil. 59
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  8.4 Process ofSoapmakhg Due to the complexity of the full boiling process,it is generally not usedin small and village scalesoapmaking. However, the semi-boiling and the cold processnormally usedby the small- scalesoapmakersare not suitable for usewith non-edible oils dueto the fact that majority of theseoils havedeepcolour and bad odour. Instead, a combination of the full-boiling and semi-boiling processis used. In the combinedprocess,the deepcoloured andbadsmelling non-edible oils to be purified are first saponified, and then grained to remove the colour and odour. The grained soap obtained is used in soapmaking together with other pale coloured oils, using the semi-boiled process. A typical formulation and processinvolving the useof neem, castor and physic nut oils is describedasfollows: Rm Mrrttviuls Nccm oil 6w Physic nut oil 3,5kg Castor oil w Caustic soda l4kg Sodium Carbonate 2Skg Common Salt Bkg The neem oil is clarified by boiling with an equal volume of water and draining the water out after settling, with the dirt from the oil. &4kg of the causticsodais then dissolvedin 25kg of water to form a 33% solution. The neemoil is then put in a boiling pan over fire and the causticsolution run into it little by little with proper stirring. When all the causticsodais usedup in the saponificationof the oil after about 4-5hoursboiling, the salt is dissolvedin a small quantity of water andis addedto the soapand stirred. The homogeneoussoap is then grained and the colouring matter in the oil separatesout from the soapand settlesdown with the excesslye. About 8Okgof water is then added to the grained soap and after proper stirring for some time, the contents of the boiling pan are allowed to settle for one night, when the pure soapfloats on the surfaceof the lye. The coloured spentlye with the impurities aredrained out, and the soap melted with somequantity of water. 61
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  It must benoted that since non-edible oils have comparatively largeproportions of free fatty acids,retardation of the saponification sometimesoccurs becausethe free fatty acids sometimes form granular soap and accumulate a considerable quantity of caustic soda, thus preventing free contact between the oil and the caustic. When retardation occurssomewater should be addedto the soapand boiled with stirring. The melted neem soap can be drained into soap moulding boxesto harden andkeep for future use,or when a continuous processis being done, the neem soap is melted with some water. Meanwhile the remaining 606kg of caustic soda is dissolved in 1608kgof water. Some of the caustic solution is added to the melted soap and the physic nut and castor oils added and stirred. The remaning caustic solution is added to the soap in bits until it is all used up to complete the saponification process. The sodium carbonate (or 25kg of 4O”Besodium silicate solution) can be introduced at this stage and stirred for about an hour. Colour and perfume may be added and the soap drained into moulding boxes. The temperature at the time of moulding, in the caseof pure soap, should not exceed70°C. 62
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  . Chapter 9 Ghana Standards Specificationsfor Soap There are certain international quality standards to which soaps,whether for laundry, toilet or medicalpurposes,haveto conform before they are sent to the market. As a check on these standards it is necessarythat samplesof soap batches comingto the market from the manufacturerarephysically and chemically analyzed. In Ghana, the National Standard Board has promulgated certain standards for different types of soap (based on the British and Indian standards for soaps). Soaps produced commercially at both the large- and small-scalelevels should satisfythesestandardsbefore they canbe marketed under the Ghana Standard Board Certificate for soaps. 9.1 Filled Hard Soap Specifications Thesesoapsare defined ashard soapscontaining fillers. They maybewhite or coloured, andshouldbewell saponified,andin addition contain fillers. Requirements Generally, the soapshould consistof alkali saltsof fatty acids; it shouldbe of firm texture, free from objectionable odour and havegood lathering properties. It shouldeither be in a form of a bar, ball, or tablet. The ingredient of the soap should be non-toxic. The soap shall also comply with the following specificchemical requirements. Total fatty matter (% by mass) Fret caustic alkali (%I by mass) Total free fat (%I by mass) Total free alkali as NazO (% by mass) Moisture (% by mass) Not less than 46 Not greater than 0.05 Not grcatcr than 0.2 Not grcatcr than 0.3 Not grcatcr than 30 63
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  9.2 Genuine HardSoap Specification This is defined as hard soap of a firm texture without the addition of any filler. Physical Requirements The soap should consist principally of the alkali salts of fatty acids, and be free from objectionable odour, and with good lathering properties. It should be in the form of a neat bar, ball, or tablet. Chemical Requirements It should be in addition to the above physical requirements havethe following composition. Total fatty matter Not less than 59% Free caustic alkali Not more than 0.05% Total caustic alkali Not mow than 0.2% Total free alkali Not mow than 0.25% Moisurc Not more than 28’X 9.3 Filled Carbolic Soap Specifications This is defined as hard soap containing fillers and phenolic substanceslike cresylic acid. Physically, the soapshould be of firm texture, free from objectionable odour, and possessgood lathering properties. The ingredient of the soap should be non-toxic. It may be in a form of a bar, tablet or ball. Chemical Requirements Total fatty matter Not loss than 46% Free cwstic alkali Not greater than O.OS% Total free fat Not grcatcr than 0.2% Phenol content Bctwccn O.S-1.(I’%, Total free alkali as Na,O Not grcntcr than 0.3% Moisture Not grcator than 30% 9.4 Toilet Soap Specification This is, by definition, soapmeant for body washingother than genuine hard soap, carbolic soap, filled soap and medicated soap. Physical Requirements The soapshall consistprincipally of alkali saltsof fatty acids; it should be of firm texture, free from objectionable odour, and 64
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  possessgood lathering properties.The ingredient of the soap should be non-toxic. Chemical Requirement In addition to the above physical requirements, the soap should have the following chemical properties: Total fatty matter Not less than 75.6% Free caustic alkali Not more than 0.05% Total free alkali Not more than 0.22% Moisture Not more than 14% 9.5 Medicated Soap This is defined asany soapother than carbolic soapfor which therapeutic claims are made. The level of active ingredient must be indicated and mustcomply with the requirement of the code of good manufacturing practice for the Cosmetic and Toiletry Industry in Ghana. The soapshouldconsistprincipally of the alkali saltsof fatty acids,be of firm texture, andfree from objectionable odour. It should possessgood lathering properties, and its ingredients should be non-toxic. Chemical Requirements % by mass of soap Total fatty matter Not less than 63 Free caustic alkali Not more than 0.05 Total free alkali Not more than 0.25 Total free fat Not more than 0.2 Matter insoluble in ethanol Not more than 2.0 Chlorides Not more than 0.8 9.6 Packaging and Marking of Soaps Packaging. Soapsshould be packaged in a suitable container made of a material that is not affected by soap. Marking. The unwrappedsoapshouldbeclearly markedwith the registered trade mark of the manufacturer. The container should be clearly marked with the following. a) manufacturer’snameandaddress,andregisteredtrade mark b) works indicating the type of soap c) batch coding or lot identification number d) minimum net weight (mass) e) country of manufacture 65
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  f) Ghana Standard(GS) number g) Ghana Standard Board Certificate Mark h) In the caseof medicated soap, there should be a conspicuous warning of the following nature 0 that use of the soap he discontinued immediately skin irritations or any other adverse reaction appears. ii) that prolonged use may be dangerous. In addition, for medicated soapscontaining mercuric oxide the product should not be used on damaged skins, e.g.cut or open skin. This warning must appear on the outer cover of the container. 66
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  Appendix 1 Some typicalformulations for soaps 1. Laundry soap - using semi-boiling process Palm oil 150kg Coconut oil 30kg Caustic soda 28kg Kaolin 15kg 2. Soft potassium soap (indigenous soap) - wing semi-boiling process Palm oil 22Skg Caustic potash 4.5kg (dissolved in 11.25kg of water) Salt 4% 3. Laundry soap - using fuil boiling process Palm oil 150kg Coconut oil 30kg Caustic soda 36.4kg Kaolin 6.8kg Salt 16.4kg 4. Carbolh soap - using fblI boiling process Palm oil 180kg Caustic soda 36.4kg Kaolin 6.8kg Salt 16.36kg Sodium carbonate 1.36kg Cresylic acid 6.8kg 67
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  5. Laundry soap- using cold process a. Palm oil 16.4kg Coconut oil 2.2kg Caustic soda 3kg (dissolved in 7kg of water) b. Palm oil 4.5kg Palm kernel oil 1.3kg Caustic soda lkg (dissolved in 4.5kg of water) 6. Toilet soap - using cold process a. Coconut oil 42.7kg Castor oil 3.7kg Caustic lye (38”Be) 23kg b Coconut oil 22.7kg Tallow (or Palm oil) 22.7kg Caustic lye (37’Be) 22.7kg 7. Transparent soap - using semi-boiling process a. Coconut oil 1.8kg Caustic soda 1.2kg (dissolved in water to obtain a 20”Be solution) Note: The method involves the production of soap stock using the above raw materials. The stock is then dried to 30-35°C. The next operation involves dissolving 50 parts of the dried soap in 50 parts of the industrial methylated spirit on moderate heat, and cooling in frames. It must be noted that the transparency of the soap is found after it has been exposed to dry air for a considerable period. 8. Liquid soap -semi-boiling process Coconut oil 182kg 50”Be Caustic potash solution 1OOkg Additional water 135litres Note: The method involves heating the coconut oil to 50°C :rnd running the caustic solution and water in and stirring: saponification takes place and the resultant soap is a 50-55% soap which is then diluted with hot softened water to obtain the desired concentration. 9. Hand protective cream for mechanics This type of soap has wide sales throughout paint, auto-accessory, hardware and drug stores. It is applied to hands and arms so as to form a barrier to paint, grease, etc while working. 68
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  Formula 88-92% soap chips5.45kg Water 32.7kg Mineral oil or lanolin 2.2kg N-Brand Sodium Silicate 4.45kg Method The soap is dissolved in hot water. The silicate is added and the mass is mixed and cooled. The mineral oil and 112gm of perfume are admixed, with stirring until uniform. The product may be filled into cans. 69
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  Appendix 2 Properties ofsoaps from different oils/fats i Texture 1Latherinn Provertv 1fairly soft 1More and stable lather Coconut very hard Plenty and fairly 4 c=, stable lather Tallow hard More and stable lathe Palm oil hard More and stable ZE’p Shea butter lather fairly hard Fairly good lather Cocoa butter hard Good lather Cleaning Property Good very good very good very good good very good good good Effect on Skin 1Uses Antiseptic washing, bathing and medicinal No effect 1washing, bathing 1and shaving 1washing, bathing 1and shaving 1washing and No effect No effect ,::::: 1bathing