• Textile Coloration and Finishing
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• v.12 no.3
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• pp.174-182
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• 2000

We prepared natural indigo/calcium hydroxide complex powder from tinctoria's leaf, according to the demand of developing new dyeing technique of natural fibre with natural indigo. FT- IR and UV/Visible spectra were operated to find the dyeing properties of synthetic indigo and natural indigo powder. Cotton, flax and silk fabrics were dyed with different pH, dye concentration and dyeing time. The colour yield of indigo dye was quite sensitive to dye bath pH and fabric. In synthetic indigo, the highest K/S value of dyed silk fabric was shown at near pH 9.0, and which of flax and cotton fabric were shown at pH 11.0. In other hand, in the case of natural indigo complex powder, the highest K/S value of dyed silk fabric was shown at near pH 8.0, and which of flax and cotton fabric were shown at pH 9.5∼pH 10. Mercerized cotton fabric dyed with natural indigo powder has a little antimicrobial activity.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.3
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• pp.359-370
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• 2011

This study analyzes the textiles design of natural indigo dyed products in Korea and Japan. In this study, a total of 556 Korean natural indigo dyed products, and 2,730 Japanese natural indigo dyed products were used for analysis. The subjects of this study were 556 natural indigo dyed products and 2,730 Japanese natural indigo dyed products selling natural indigo dyed products which were found using search engine keywords of natural indigo dyeing and natural dyeing. Research and analysis was treated regarding the products, items, patterns, and the representation techniques of the patterns. The results of this study are as follows. In the pattern used for natural indigo dyed products, 71.4% of Korean products have no pattern, but 77.1% of Japanese products have patterns. On the representation techniques of the patterns, Korean products used tie-dyeing and a dip patterned fabric. While in the Japanese products, the most frequent patterning techniques were paraffin dye, followed by tie-dyeing, yarn-dyed and weaving, screen printing, and yarn-dyed and knitting. Regarding the kinds of patterns for natural indigo dyed products, only 8 kinds of patterns were used in Korean products; however, over 50 kinds of various patterns were used in Japanese products. Most patterns in the Korean products were ion patterns made by tie-dyeing. While in the Japanese products, the most frequent patterns were stripe patterns, followed by flower, dot, and ion patterns. Based on these research results, the problems of the textile design of Korean natural indigo dyed products were that most of the products have no pattern, and even though there were patterns, they lacked variations between the products. While in the case of Japan, they used the traditional and modem patterns of various textile representation techniques.

• The Research Journal of the Costume Culture
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• v.24 no.6
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• pp.777-787
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• 2016

This study was carried out in order to provide useful data for planning fabrics of summer eco-friendly fashion products. The fabrics used in this study were four cellulose fibers: cotton, cotton/mulberry blended, flax, and flax/lyocell blended. Dyeing with natural indigo was carried out under three different reducing conditions (i.e., general, eclectic, and eco-friendly) that have different reducing agent and pH levels, and hydrosulfite and glucose were used as a reducing agent. The dye uptake (K/S value) of fabrics dyed with natural indigo by a reducing condition was the highest at 660nm. Regardless of the fabrics, dye uptake was the highest under the general reducing condition and the lowest under the eco-friendly reducing condition. Under different reducing conditions, the dye uptake of natural indigo fabrics with the maximum absorption wavelength indicated a difference. The colorfastness of cellulose fabrics that were dyed with natural indigo had a rate of 4 to 5 except for rubbing fastness, which indicated good colorfastness. Additionally, natural indigo-dyed cotton and flax fabrics had good antibiosis. When the color characteristics of fabrics dyed with natural indigo were measured, all of the three reducing conditions created purple blue (PB) colors, and the color characteristics of dyed fabrics by reducing condition and fabric showed significant differences.

• Journal of the Korean Home Economics Association
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• v.45 no.4
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• pp.53-59
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• 2007

We need to diversify the colors by natural dyeing for promotion and extention of the natural dyes market, because natural dyestuffs have the limitation the number of the colors to express, compare to synthetic dyestuffs. It was investigated that wool and silk fabrics could be dyed to green colors using natural mugwort and indigo as one of color diversification, in order to express green color that is difficult to be shown by natural dyeing. The mugwort dyebath was prepared to concentration of $25{\sim}100g/l$ using dried mugwort plant and indigo dyebath was prepared to concentration of $5{\sim}20g/l$ using natural indigo powder. Wool fabrics and silk fabrics were dyed to green(GY, G, BG in Munsell color wheel) by two batch methods using the mugwort and indigo dyebaths. the mugwort dyeing was applied at $80^{\circ}C$ for 20minutes and indigo dyeing applied for $5{\sim}7$ minutes in room temperature. The colorfastness to drycleaning and abrasion of the dyed fabrics were shown good as grade 4-5 or 5.

• Korean Journal of Human Ecology
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• v.22 no.2
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• pp.365-374
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• 2013

The purposes of this study were to evaluate the color characteristics and color sensibility of mulberry/cotton blended fabrics dyed with indigo, the natural dye, and analyze effects of them on color preferences. The values of CIE $L^*$, $a^*$, $b^*$ $C^*$, h were calculated for the color characteristics of indigo-dyed fabrics, and their hue, value, and chroma were calculated according to the Munsell color system. Fifty male and female college students evaluated the color sensibility of nine types fabrics dyed with indigo on a seven-point scale. The data were analyzed by descriptive statistics, factor analysis, Kruscal-Wallis test, correlation analysis, and regression analysis. The mulberry/cotton blended fabrics naturally dyed with indigo showed the characteristics of PB color tones, low value, and low chroma. The color sensibilities of fabrics dyed with indigo were classified into four factors: 'classic', 'sporty', 'elegant' and 'natural'. There were significant differences according to the fibers and the repeating times of dyeing in the color sensibility for the fabrics. Cotton fabrics were evaluated to be more classic, sporty, elegant, and natural than the mulberry/cotton blended fabrics, and the deeper the color, the more classic, sporty, and elegant the fabric was evaluated. The students preferred the indigo dyed fabrics which have more classic, sporty, and natural sensibility. There were significant relationships between the color sensibilities and colorimetric properties of the fabrics dyed with indigo. The color preferences of the dyed fabrics with indigo were found to be influenced by the 'classic', 'sporty', 'natural' of color sensibility.

• Korean Journal of Medicinal Crop Science
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• v.21 no.3
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• pp.213-219
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• 2013

This study was carried out to find out the optimum method of preparation of indigo standard solution and its stability, and to investigate the indigo contents in Niram, blue dye extract, from a total of 7 indigo plants and 34 breeding lines of Persicaria tinctoria H. Gross. Proper solvent for indigo standard was dimethyl sulfoxide (DMSO), and appropriate concentration was 1 mg of indigo in 10 mL of DMSO. Absorbance value of UV/Vis Spectrophotometer at 620 nm of standard solution was changed decreasingly 12 hours after the preparation of standard solution irrespective of the storage conditions such as temperature and light. Average value of absorbance of 8-fold diluted standard solutions prepared daily during 16 days was $0.210{\pm}0.005$, indicating the powder of indigo compound was stable chemically. Calibration curve was made for quantitative analysis of indigo of 7 Niram samples, and indigo contents ranged from 0.69% to 18.76% showing relatively larger variation. Across all 34 breeding lines, the range of indigo content was from 7.9 mg to 56.4 mg per 100 g of fresh leaves, averaging 25.2 mg of indigo content and showing a 47.7% coefficient of variation.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.7
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• pp.736-747
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• 2011

This study investigates the current status and dyeing properties of various natural indigo powder dyes in the domestic market. Products from India, China, Europe are sold in the market and only a few manufacturers provide recommendation for the method of dyeing and information on the additives. Through the market research and the preliminary investigation on 21 products, 11 were selected for the dyeing experiment which include 3 Indian, 3 Chinese, 2 German, and 1 Pakistani origin indigo reduced powders, and 2 Indian origin dried indigo leaf powder. The two dyeing methods used were the precipitation method and the fresh juice method, both at $10^{\circ}C$, $25^{\circ}C$, and $60^{\circ}C$. Color difference, K/S value, and colorfastness of dyed cotton fabrics were examined. Indian reduced indigo powder showed the highest K/S value, deep dyeing, and the best color fastness. Chinese reduced indigo powder resulted in a more greenish and bluish color. Powders of dried indigo leaves were easy to use but resulted in a pale color due to low dye uptake.

• Textile Coloration and Finishing
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• v.15 no.4
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• pp.32-38
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• 2003

To get the variety of color by natural dyeing, cotton and silk fabrics were dyed with natural indigo and safflower in turn. The two ways of dyeing processes were carried. First, silk and cotton fabrics were dyed repeatedly in safflower dyebath to five times to get the five fabrics dyed in different shades. And then indigo dyeing process was carried on the top of the dyed fabrics with safflower. In second way, the fabrics were dyed in five stages of shade by repetition of dyeing process in indigo dyebath. And then safflower dyeing was carried on the top of the dyed fabrics with indigo. When indigo dyeing process was added on the top of the fabrics dyed in five shades with safflower, the color differences decreased between five shades of fabrics, their color values got similar in hue, shade and chroma. When safflower dyeing process was added on the top of the fabrics dyed in five shades with indigo, the fabrics showed different hue of colors between red and blue of Munsell color circle such as RP, P and PB. Like almost of fabrics dyed with plants materials, the lightfastness and laundering fastness of dyed samples were poet and drycleaning fastness were good.

• Textile Coloration and Finishing
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• v.33 no.4
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• pp.202-209
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• 2021

Natural dyes are more expensive than synthetic dyes and the dyeing process, which is mainly immersion of dye, is complicated. For this reason, relatively small-scale production methods were predominant. However, awareness and interest in environmental sustainability is rising globally, and the use of synthetic dyes causes various environmental problems such as wastewater and CO₂ emission, so the consumption of natural dyes is increasing. In addition, interest in digital textile printing, an eco-friendly dyeing method that can produce products of various designs and uses less water, is growing. In this study, natural indigo dye (Indigofera tinctoria) was used as a raw material for Digital Textile Printing ink, and ¹⁴C (Biocarbon) present in it was measured to confirm whether it was derived from natural ingredients. The performance was confirmed by testing the pH, viscosity, electrical conductivity, surface tension, and particle size analysis of natural indigo ink. In addition, the performance of natural indigo DTP ink and printing fabric was evaluated by inspecting the change in color fastness and corresponding index substances before and after digital printing with natural indigo DTP ink on textiles. Through this, the possibility of commercialization of DTP ink and printing fabric using natural indigo was confirmed.

• Textile Coloration and Finishing
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• v.24 no.4
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• pp.253-259
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• 2012

In this work, the natural indigo production process from Polygonum tinctorium was balanced based on the traditional Niram method in Korea. A standard procedure was determined considering the conditions of indican extraction from plant material, the amount of alkali for precipitation, storage of extract, etc. The effect of experimental conditions on the yield of crude dye was investigated. The contents of indigo and indirubin of the crude dyes were analyzed by HPLC. Increase of the amount of crude dye was observed within 1-2.5 days of extraction time. Longer extraction beyond 2.5 days resulted in a slight decrease in the amount of crude dye. There was no consistency in terms of indigo content depending on extraction pH. We found that the storage of extract or harvested plants affected adversely to dye yield and dye quality. Based on the lab scale extraction, large scale extraction was performed for 2-2.5 days in water and 2.0-2.5 g/L of $Ca(OH)_2$ was applied for precipitation of indigo dye. We obtained natural indigo dye containing about 15% of pure indigo in scale-up production using whole plant except root.