• Textile Coloration and Finishing
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• v.17 no.4 s.83
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• pp.1-6
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• 2005

We studied the degree of variety of indigo for the electrochemical redox reaction in addition of reducing agent and the electrokinetic parameters. The electrokinetic parameters such asthe number of electron and the exchange rate constant were obtained by cyclic voltammetry. With increasing scan rate, the reduction currents of indigo were increased and the reduction potentials were shifted to the negative direction. As the results, the reduction processes of the indigo were proceeding to totally irreversible and diffusion controlled reaction. Also, exchange rate constant ($k^0$) and diffusion coefficient ($D_0$) of indigo were decreased by increasing concentration of reducing agent. We found that the less concentration, the more easily diffused and electron transferred and the product was more stable.

• Textile Coloration and Finishing
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• v.21 no.2
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• pp.29-39
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• 2009

The color mixture, obtained from Indigo and Japanese pagoda tree, was applied to cellulose fibers such as cotton, linen and rayon to diversify color gamut of natural dyes. The color mixture was tried with two different methods. The first process was that cellulose fibers were dyed with $5{\sim}25%$ owf Japanese pagoda tree solution, and then dyed 1 to 4 times with Indigo. The second process was dyeing 1 to 7 times with Indigo, followed by dyeing with $5{\sim}25%$ owf Japanese pagoda tree solution. K/S value of the dyed fibers with one colorant and color mixture increased in the order of linen, cotton, rayon. It was also found that the first process could give higher K/S values than the second process.

• Textile Coloration and Finishing
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• v.20 no.3
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• pp.18-24
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• 2008

The purpose of this study is to develop the dyeing method with dry leaves of indigo plant. Coloring matter was extracted from dry leaves of indigo plant with hot sodium hydroxide solution. The extract was reduced with sodium dithionite, and it was used for dyeing cotton fabrics under various conditions. UV-visible absorption spectra of extract, reduction rate of extracts by reducing agent, and the surface color of dyed cotton, lightfastness were examined. For the initial 20 minutes, the absorbance of indigo solution rapidly decreased. However, several hours later, the decreasing rate retarded. By repeating the dyeing process, the shade looked deeper and deeper. At $30-40^{\circ}C$, the value of K/S reached the highest point. The concentration of indigo solution in dye bath seemed to playa critical role for the reaction of the reducing agent. It was observed that the surface color of cotton fabrics was getting bluish and its degree of value and chroma seemed slightly decreased as the K/S value was increasing. The lightfastness was clearly enhanced by increasing the K/S value.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.2
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• pp.325-336
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• 2002

This study investigated color change of combination dyeing silk fabrics dyed with Turmeric extracts and Gardenia extracts after dyeing of Indian indigo. Experimental variables include the condition of dyeing time and concentration of Turmeric extracts, Gardenia extracts, arid dyeing cycle of Indian indigo. Surface color of silk fabrics dyed with Turmeric 77tracts after one cycle dyeing, two cycles dyeing, four cycles dyeing of Indian indigo was changed from 5.1GY to 0.3GY, 1.5G to 3.5GY and 6.5G to 5.8GY by increase of concentration of Turmeric extracts. On the other hand, Surface color of silk fabrics dyed with Gardenia extracts after one cycle dyeing, two cycles dyeing, four cycles dyeing of Indian indigo was changed from 7.5Y to 3.9Y, 1.2GY to 6.7Y and 4.0GY to 8.6GY by increase of concentration of Gardenia extracts. Its range of surface color was changed to green and yellowish green by increase of dyeing time with concentration of Turmeric extracts. On the other hand, its range of surface color was changed to yellowish and yellow by increase of dyeing time with concentration of Gardenia extracts.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.2
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• pp.212-223
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• 2017

This research investigated the screen printing method for natural indigo dye on cotton fabric. We examined four types of thickening agents (arabic gum, guar gum, indalca, and CMC) based on their ability to retard the oxidation of natural indigo print paste while the paste remained on the screen frame. The results indicated that the retardation of arabic gum towards oxidation was the greatest among the four types of thickening agents. The highest K/S value of the printed cotton was observed with a dye concentration of 50g/L fermented indigo powder. The best printing results were obtained when the duration of dye efficiency was tested for the 10 minutes of the dye paste remaining on the screen with a thickening agent concentration of 26.56% that represented 530 cps viscosity. The test of colorfastness to washing and rubbing of the printed cotton resulted in grade 5, and the colorfastness to sunlight resulted in grade 4. Chinese traditional Naminwhapo printing was reproduced on cotton fabric using the natural indigo printing method derived from this study.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.12
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• pp.1963-1970
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• 2008

Natural indigo dye in powder form was prepared by modifying traditional Niram method, using $Ca(OH)_2$ instead of baked oyster powder for precipitating indigo dye. The prepared dye was applied to dyeing Tencel fabrics to investigate the effect of experimental conditions for the optimization of dyeing process. The indigo dye powder contained 15.2%(w/w) of indigo content and 0.757%(w/w) of indirubin content on the basis of HPLC analysis. Maximum dye uptake was obtained at $60^{\circ}C$ for 20min. Almost saturated dye uptake was obtained at 2g/L of sodium hydrosulfite concentration up to 4g/L of indigo dye and then slowly increased for further increase of sodium hydrosulfite. Whereas at higher indigo dye concentration(8g/L) more than 3g/L of reducing agent concentration was required for obtaining the maximum dye uptake. At the same indigo dye and reducing agent concentration, K/S value of the sample dyed without sodium hydroxide(pH 5.75) was 15.19, much higher than one dyed in alkaline condition(K/S 5.76). There was no difference in colorfastness ratings among samples with different color strength. However, more fading was occurred for the sample with low color strength.

• The Research Journal of the Costume Culture
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• v.20 no.4
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• pp.463-474
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• 2012

The purpose of this research was to find the suitable dyeing method for dyeing cotton fabric into indigo blue color using the raw indigo powder dyes sold in the Korean market. The research focused primarily on the comparison of the non-reduced dyeing method and the reduced dyeing method. The dyeing effects using different dyeing temperatures ($2{\sim}80^{\circ}C$) and different concentrations of reducing agent and alkali were also investigated. It was found that the reduced dyeing method must be used for dyeing cotton into indigo blue color using the commercial raw indigo powder dyes. The best result was obtained by $20^{\circ}C$ dyeing with the $40^{\circ}C$ dyeing giving a comparable result. The intensity of the blue color could be enhanced by increasing the alkali concentration. The non-reduced dyeing could not dye cotton fabric into indigo blue color at any given dyeing temperatures ($2{\sim}80^{\circ}C$). The reduce-dyed cotton fabrics showed a gradual color change upon repeated washing and extended sunlight exposure, the most color change occurring after the first two washing cycles and the first 5 hours of sunlight exposure. The standard tests of colorfastness showed that the reduce-dyed cotton fabrics had good to excellent colorfastness whereas the colorfastness of the non-reduce-dyed cotton fabrics were mostly poor.

• The Research Journal of the Costume Culture
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• v.19 no.2
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• pp.376-388
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• 2011

The purpose of this study is to examine the types and characteristics of Chinese indigo dyed designs performed until today in private houses of Chinese minority races and to examine the modern value of traditional dyeing crafts of minority races by investigating the cases of utilizing modern private Chinese indigo dyed designs. As the research methodology for theoretical study about the history of Chinese traditional pattern dyeing, the origin, types and characteristics of Chinese indigo dyed designs, the preceding research data, photo data, and Internet data were utilized, and for the empirical research on Chinese traditional dyeing techniques and the cases of utilizing today Chinese indigo dyed designs, the on-site survey on Guizhou and Yunnan was conducted during February and March 2008 and the data were collected and analyzed. Based on the results of this research, it was found that Chinese indigo dyed designs represented Chinese traditional pattern dyeing, which was inherited and developed mainly in Chinese minority races and Chinese. It could be seen that according to geographical distribution and characteristics of each race, the types and characteristics of dyeing techniques were formed, which are classified into the batik of the Miao of Guizhou in the Chinese southwestern region, the tie-dyeing of Bai of Yunnan, and Chinese blue calico(resist printing) of Chinese private houses in the Hunan and Huseo regions, and these represent the three typical Chinese dyeing techniques today. Based on the results of empirical research on the utilizing cases, focusing on the traditional living handicrafts of Chinese minority races, traditional cultural articles, and artworks, the modern values such as practical, cultural, and artistic values of Chinese indigo dyed designs could be rediscovered.

• Science of Emotion and Sensibility
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• v.20 no.3
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• pp.3-12
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• 2017

This research was carried out in order to suggest useful data for planning fabrics of summer eco-friendly fashion products. For this purpose, four cellulose fabrics were dyed with natural indigo under three different dyeing conditions, then, their colorimetric properties and color sensibilities were evaluated, and their influences on color preferences were analyzed. All cellulose fabrics naturally dyed with indigo showed the characteristics of PB color tones, middle and low value, and low chroma. Color characteristics were significantly different according to fiber type and dyeing condition. The color sensibilities of the fabrics dyed with indigo were classified into three factors: sporty, classic and natural. These sensibilities showed partially significant differences according to fiber type and dyeing condition. Also, there were partially significant relationships between color characteristics and the color sensibilities of the fabrics dyed with indigo. The color preferences of the dyed fabrics with indigo were found to be influenced by the sporty and classic of color sensibility and $L^*$ of color characteristics.

• Textile Coloration and Finishing
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• v.32 no.4
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• pp.193-198
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• 2020

In this study, the validity of extracts from food waste as biocatalyst for indigo reduction was examined. Dried food wastes such as apple peel and corn waste were water-extracted and freeze-dried. The reducing power of extracts for indigo was evaluated by the oxidation-reduction potential(ORP) measurement of reduction bath and color strength(K/S value) of the fabrics dyed in the indigo reduction bath. Total sugar contents of the apple peel and corn waste extracts were 60.56% and 62.36%, respectively. Antioxidant activity was 64.78% for the extract of apple peel and 7.96% for the extract of corn waste. Indigo reduction took place quickly with both extracts, and maximum color strength was obtained up to 15.91 and 12.11 within 1-3 days, respectively. The oxidation-reduction potential of reduction bath was stabilized in the range of -500 ~ -620 mV according to the kinds of food waste and the extract concentration. At higher concentration of the extracts, reduction power was maintained for longer time and stronger color strength was obtained. Compared to sodium dithionite, the reducing power of the studied extracts was lower, but the reduction stability was superior to it. The studied extracts were effective biocatalyst as biodegradable and safe alternatives to sodium dithionite for indigo reduction.