Sabina Bračko | University of Ljubljana (original) (raw)

Papers by Sabina Bračko

Tekstilec, Nov 14, 2019

Introduction Th e memorial restoration of a certain event or sensation (e.g. colour) is far from ... more Introduction Th e memorial restoration of a certain event or sensation (e.g. colour) is far from being perfect. Contrary to a common belief, our memory is not infallible. As confi rmed by several investigations, our colour memory is rather poor and the sensation of a colour is not always remembered accurately [1−3].

Proceedings - The Eleventh International Symposium GRID 2022

When studying the process of photodegradation, we often deal with the durability of the individua... more When studying the process of photodegradation, we often deal with the durability of the individual ink colour components, the durability of the printing material or the durability of the ink on the printing material. Less frequently, ink degradation in the solution is compared to the print. However, it is essential to consider all the crucial external and internal factors that influence the photodegradation process in the context of the durability of printed materials. When studying photodegradation, external factors such as light, temperature and humidity are relatively easy to control. On the other hand, the control of internal factors in the photodegradation process is much more complex since the internal factors are related to the composition of the ink used, the substrate and the physical and chemical processes between them. The study aims to analyse the complex degradation process of prints made with an ink-jet printer compared to the degradation of the same inks in an aqueous...

Smart Textiles for Medicine and Healthcare, 2007

Color Research & Application

TEKSTILEC, 2021

Colours are one of the most important factors in everyday life. The exact number of existing colo... more Colours are one of the most important factors in everyday life. The exact number of existing colours is not yet fully known. Nevertheless, people are known for having poor colour memory. The ability to remember colours depends both on the characteristics of an individual and the situation in which the colour needs to be recalled. The field of colour memory (perception and memory of unusual colours) has been very poorly researched. The aim of this study was to analyse long-term colour memory for selected associative colours, comparing it with short-term colour memory. The research approach was based on observation, with observers observing for a period of time a particular colour, image, or a descriptively given reference colour. Colour was treated sepa¬rately from associations in the first part, and related to associations in the second and third parts. The first part contained all the reference colours shown independently of associations, the second part contained grayscale images ...

In this paper the lightfastness of flexographic prints was studied. Studied prints were obtained ... more In this paper the lightfastness of flexographic prints was studied. Studied prints were obtained using conventional solvent based and UV curing flexographic inks. The prints were made on polypropylene(PP) and polyvinyl chloride (PVC) foils. Applied polymer substrates were treated with Corona process before printing and their surface energy was tested with testing pen. Flexographic printing is frequently used for polymer packaging products and the lightfastness of obtained prints is extremely important. Low lightfastness prints are changing and/or loosing colors. Such prints have negative effect for sellers of various goods packed in polymer package. It is well known that numerous flexographic prints on polymer substrate are often placed on the shelves in the market were these prints are more or less exposed to sunlight and the only protection are windows. The lightfastness of prints is an ability to retain its color strength and resist fading upon exposure to light (sunlight or ligh...

May 2010, 2010

We investigated the printability of fibrous synthetic papers with ultraviolet (UV) inkjet technol... more We investigated the printability of fibrous synthetic papers with ultraviolet (UV) inkjet technology. Cyan, magenta, yellow, and black (CMYK) color fields were printed on two types of fibrous synthetic papers using two different wide-format UV inkjet printers. Spectrophotometric and densitometric measurements were performed on CMYK color fields with different ink coverages, along with a microscopic analysis of unprinted paper, black prints with 100% ink coverage, and a print mottle of magenta and black prints. Colorimetry and optical densities of the CMYK prints were qualitatively and quantitatively compared. Color deviations in CMYK prints were affected by paper type and were dependent on the UV inkjet printer used.

Tehnicki vjesnik - Technical Gazette, 2019

Three frequently used formulas and their power function modifications were used to calculate the ... more Three frequently used formulas and their power function modifications were used to calculate the colour differences after the exposure to light and to study the stability of ink jet prints by spectrophotometric measurements. The prints were exposed to the simulated daylight of different spectral composition at constant conditions of temperature and relative humidity. According to the results, the black prints were the least affected and the magenta prints exhibited the biggest colour differences. The most resistant have proven to be the prints on archival paper which contained no optical brightening agents. The presence of shortwave radiation between 320 and 300 nm additionally diminished the resistance of prints. The same conclusions were obtained regardless of the colour difference formula applied, with one exception. Generally, the CIEDE2000 formula performed the best, especially when comparing samples with a smaller colour difference.

Coloration Technology, 2018

Journal of Imaging Science and Technology, 2010

Despite the evident success of conventional onedimensional (1D) bar codes and their role in autom... more Despite the evident success of conventional onedimensional (1D) bar codes and their role in automatic product identification, logistics, supply, and retail, these 1D technologies can encode only a limited amount of data and are susceptible to damage and obscuration. On the other hand, two-dimensional (2D) codes which began appearing in the 1980s are becoming more and more popular because of their ability to encode a large amount of data in a small area. They can also be read even if they are partially damaged or erased. Because of their advantages in comparison to linear bar codes and their increasingly frequent use the authors analyzed two 2D codes (DATA MATRIX code and QR code). The purpose of our research was to determine the lowest raster tone value for each printing color and each printing technique which would enable the 2D code reading with two different readers. For testing the readability of codes, lightfastness, accelerated aging, and water resistance were used. Codes were created and printed in four process inks (cyan, magenta, yellow and black), each of them in the following raster tone values: 15%, 20%, 25%, 30%, 50%, and 100%. Samples were printed using three different digital printing technologies (ink jet, laser, and magnetography). After printing, the samples were illuminated by Xe light, exposed to accelerated aging (at 80°C and 65% relative humidity) for six days, and immersed in water to determine their water resistance. All printed samples, before and after illumination and accelerated aging, were read with laser and charge coupled device based readers, and the lowest raster tone value of the code for each printing technique and each printing ink was determined.

Journal of Imaging Science and Technology, 2011

... 1–9. W. Tracy, Letters of Credit: A View of Type Design (David R. Godine, Boston, 2003), pp.1... more ... 1–9. W. Tracy, Letters of Credit: A View of Type Design (David R. Godine, Boston, 2003), pp.19, 30–32. ... ISO 8791/2–1990, Paper and board: Determination of roughness/ smoothness (air leak methods)—Bendtsen method (ISO, Geneva), www.iso.org. ...

Journal of Cultural Heritage, 2013

The quality of a book reprint depends on several factors, e.g. paper, typesetting, reproduction o... more The quality of a book reprint depends on several factors, e.g. paper, typesetting, reproduction of illustrations, printing and bookbinding. The quality of the 1958 and 1988 reprints of the fairytale edition from 1944 designed by the Slovenian architect Jože Plečnik was studied using standard and other noninvasive testing methods, e.g. microscopic and spectroscopic techniques, sonic velocity, Young's modulus of elasticity, surface topography and image analysis. The chemical, physical and colorimetric properties of papers and typographic tonal density were analysed. The results showed that the reprints do not correspond to the originals. Some of the differences in the reprints, if compared with the original (e.g. typographic tonal density), could have been easily avoided, while others (e.g. structural and optical properties of paper) remain unavoidable, mainly due to the influence of internal and external factors on the ageing. The ageing process influences paper properties, since optical properties deteriorate in time. It has been concluded that a precise and systematic study of the properties of an old book should be performed before the preparation of a reprint. The results of the research have shown that the applied methods are useful and satisfactory for the characterisation of the paper properties and typography, and can be of use at the analysis of printing ink and illustration reproduction.

Dyes and Pigments, 2001

The interactions between an anionic dye and two cationic surfactants were studied by conductometr... more The interactions between an anionic dye and two cationic surfactants were studied by conductometry. The specific conductance of dye-surfactant mixtures was measured at three different temperatures in water-ethanol mixed solvent, containing 5, 10, 15 or 20 wt.% of ethanol. The equilibrium constants and other thermodynamic functions for the process of dye-surfactant ion pair formation were calculated on the basis of two theoretical models. The results showed that the presence of ethanol decreases the tendency for ion pair formation. According to the results, long range as well as short range interactions are responsible for the formation of the ion pair. The importance of long range electrical forces is basically to bring the dye anion and the surfactant cation close enough to enable the action of short range interactions whose contribution represents the major part of the standard free enthalpy change for the formation of the anionic dye-cationic surfactant ion pair.

Dyes and Pigments, 2000

The formation of a dye±surfactant ion pair was studied using a conductometric method in which the... more The formation of a dye±surfactant ion pair was studied using a conductometric method in which the conductance of aqueous solutions of C.I. Acid Orange 7 was measured in the presence of the cationic surfactants dodecylpyridinium chloride or hexadecylpyridinium chloride at four dierent temperatures. Two theoretical models to calculate the relevant equilibrium constants were derived. Both methods of calculation led to similar results that were in good agreement with other methods of investigation of dye±surfactant association. The results have shown that an increase in temperature lowers the tendency for ion pair formation as the equilibrium constants decrease with increasing temperature. A comparison of the behaviour of both surfactants revealed that the surfactant which contained the longer hydrophobic chain had a stronger tendency to associate with the dye and the corresponding equilibrium constants were considerably higher than those recorded for the surfactant with the shorter aliphatic chain. Such ®ndings indicate that not only long range electrostatic forces but also short range, non-electrostatic interactions have a signi®cant in¯uence on dye±surfactant ion pair formation.

Coloration Technology, 2009

Colour constancy of prints with vat dyes on cotton fabrics was investigated by computing the CMCC... more Colour constancy of prints with vat dyes on cotton fabrics was investigated by computing the CMCCON02 colour inconstancy index with the key element CAT02 for chromatic adaptation transform. The results show that the highest changes in colour appearance can be expected when the average daylight is replaced with fluorescent light. If D65 daylight is replaced with some other type of daylight, such as D50 or D55, only minor colour deviations occur which do not substantially change the colour appearance of the prints. The analysis of the influence of the lightness and chromaticity of prints shows that the chromaticity of the samples significantly affects their colour constancy. The change of appearance of the prints with lower chroma because of changed illumination conditions is less probable. The influence of a dye blend composition was also investigated. On average, multicoloured dye blends have proved to be more colour constant.

Diseño de portada: candelaInk Este libro ha sido debidamente examinado y valorado por evaluadores... more Diseño de portada: candelaInk Este libro ha sido debidamente examinado y valorado por evaluadores ajenos a la Universidad de Alicante, con el fin de garantizar la calidad científica del mismo. Reservados todos los derechos. Cualquier forma de reproducción, distribución, comunicación pública o transformación de esta obra sólo puede ser realizada con la autorización de sus titulares, salvo excepción prevista por la ley. Diríjase a CEDRO (Centro Español de Derechos Reprográficos, www.cedro.org) si necesita fotocopiar o escanear algún fragmento de esta obra.