Dye Yield, Color Strength and Dyeing Properties of Natural Dyes Extracted from Ethiopian Dye Plants (original) (raw)

With the aim of scientific investigation on natural dye yielding plants of Ethiopia, few dye plants which are traditionally used for cotton dyeing in Ethiopia were selected. Crude dyes in powder form were isolated after evaporation of aqueous extracts. The color strength and color mass equivalences of the aqueous extracts compared to synthetic dye (commercial C I Reactive Red 4) were determined. Calculation of color equivalence gives an idea of the necessity of using large quantities of raw dye plant to get a particular depth of shade compared to synthetic dye. Cotton fabric was dyed without and with alum and iron (II) sulphate mordants. The dye uptake (K/S), CIE L*a*b*, wash and light fastness results indicated that dye plants traditionally used in Ethiopia for cotton dyeing have considerable potential for application as a source of natural dyes. Attempts were made to correlate crude dye yield and color strength of extracts. However, no relationship existed between these parameters. This is attributed to the absence of knowledge of exact coloring components and chemical structures of crude dye obtained after evaporation of dye extracts. The emphasis of the paper is on the color strength, color yield equivalence compared to commercial C I Reactive Red 4 and dyeing behavior without and with mordant. No attempt was made for dye chemical structure determination due to lack of purity of isolated dye from aqueous extracts. Use of aqueous extract without further purification is a common practice of dyeing with natural dyes.

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