• Textile Coloration and Finishing
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• v.27 no.2
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• pp.155-163
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• 2015

In dyeing cotton fabric with the Indigo Pulverata Levis, this research examined the effect of the sodium dithionite($Na_2S_2O_4$). For the separation of the Indigo-calcium hydroxide complex in the alkaline solution of the Indigo Pulverata Levis, the reduction with the $Na_2S_2O_4$ at $25^{\circ}C$ was more effective than the solution boiling. The concentration of Indigo in the cotton fabric increased with the increase of Indigo Pulverata Levis, but the concentration of indirubin did not increase particularly. The optimum temperature for the reduction was $60^{\circ}C$, and K/S value of dyed fabric decreased at over $60^{\circ}C$. The concentration of indigo and indirubin in the cotton fabric decreased as $Na_2S_2O_4$ concentration increased. In treating cotton fabric dyed with the Indigo Pulverata Levis by the $Na_2S_2O_4$, the concentration of indirubin decreased and the surface color of dyed cotton changed from purple blue to blue while the treatment temperature was getting higher.

• Textile Coloration and Finishing
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• v.21 no.3
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• pp.10-18
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• 2009

Dyeing process of the natural indigo powder onto ramie and silk fabrics was investigated by using glucose and calcium hydroxide as a reducing system. Effect of reduction and dyeing conditions such as temperature and time of reduction/dyeing, and concentrations of glucose and calcium hydroxide on the dyeing process were explored. Indigo powder was obtained by drying the conventional niram paste in an oven at $50^{\circ}C$. Color strength of the dyed fabrics was evaluated by K/S value measured at the wavelength of maximum absorption(${\lamda}$max). Munsell color coordinates(H V/C) were used to compare fabric colors of ramie and silk. Ramie fabric showed purple-blue color for all the temperature and time. On the contrary, silk fabric showed wide range of color including brown, brown-green, green at the different temperature. With the increase of K/S value, the coordinate of value(lightness) decreased for both of ramie and silk fabrics. The coordinate of hue(shade) changed drastically with the increase of K/S value for silk fabric, compared with that of ramie fabric which showed nearly constant value at the whole range of K/S value. Optimum concentrations of calcium hydroxide were for 6 g/L for ramie and 4 g/L for silk at $60^{\circ}C$ and 50 min. K/S value increased with the indigo concentration. Maximum K/S value was shown at $10{\sim}12$ g/L of glucose concentration. For both of ramie and silk fabrics, the colorfastness of washing and light was lower than that of rubbing. All the colorfastness values were improved with the increase of color strength.

• 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.

• KSBB Journal
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• v.28 no.5
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• pp.295-302
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• 2013

Indigo is utilized in various industries including textile dyeing, cosmetics, printing and medicinal products and its reduced form, leuco-indigo, is mainly used in these process. Chemical reducing agent (sodium dithionite, sodium sulfide, etc.) is preferred to use for the formation of leucoindigo in industry. In traditional indigo fermentation process, microorganisms can participate in the reduction of indigo and thus it has been known to reduce environmental pollution and noxious byproducts. However, in fermentation method using microorganisms it is difficult to standardize large scale production process due to low yield and reproducibility. In this study, we attempted to develop the indigo reduction process using microbial flora which was isolated from naturally fermented indigo vat or deduced by metagenomic approach. From the results of library analyses of PCR-amplified 16S rRNA genes from the traditional indigo fermentation vat sample (metagenome), it was confirmed that Alkalibacteriums (71%) was distinctly dominant in population. Some strains were identified after confirming that they become pure culture in nutrient media modified slightly. Four strains were separated in this process and each strain showed obvious reducing ability toward indigo in dyeing test. It is expected that the analyzed results will provide important data for standardizing the natural fermentation of indigo and investigating the mechanism of indigo reduction.

• Textile Coloration and Finishing
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• v.13 no.5
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• pp.41-41
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• 2001

In this study, synthetic fiber fabrics such as polyester, nylon 6, acrylic and acetate were dyed with indigoid vat dye. The effects of the composition of alkaline reduction, dyeing time and dyeing temperature on color strength and color fastness of the fabrics were investigated. Also the color fastnesses to wash and light of the dyed fabrics were studied. In dyeing of polyester, nylon, acrylic and acetate fiber fabrics with indigo vat dyes, it appears that these fabrics have high values of K/S up to Ig/L of sodium hydroxide and 6g/L of reducing agent. Indigo vat dyeing for synthetic fiber fabrics was verb fast, and lead to dyeing equilibrium within twenty minutes. The K/S values of dyed fabrics did not changed in dye concentration more than 10% o.w.f.. Synthetic fiber fabrics dyed with indigoid dyes had bad light fastness.

• Textile Coloration and Finishing
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• v.13 no.5
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• pp.329-335
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• 2001

In this study, synthetic fiber fabrics such as polyester, nylon 6, acrylic and acetate were dyed with indigoid vat dye. The effects of the composition of alkaline reduction, dyeing time and dyeing temperature on color strength and color fastness of the fabrics were investigated. Also the color fastnesses to wash and light of the dyed fabrics were studied. In dyeing of polyester, nylon, acrylic and acetate fiber fabrics with indigo vat dyes, it appears that these fabrics have high values of K/S up to Ig/L of sodium hydroxide and 6g/L of reducing agent. Indigo vat dyeing for synthetic fiber fabrics was verb fast, and lead to dyeing equilibrium within twenty minutes. The K/S values of dyed fabrics did not changed in dye concentration more than 10% o.w.f.. Synthetic fiber fabrics dyed with indigoid dyes had bad light fastness.

• The Research Journal of the Costume Culture
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• v.19 no.3
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• pp.612-621
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• 2011

The process of making or cultivating indigo dyes is very cumbersome and complex. The dye extraction and dyeing methods using general plant dye, moth repellent dye, fast acting natural dye, and other dyes are very different. This research investigates the extraction of indigo dye and liquid dye extraction of polygonum(indigo) plants using calcium oxide water. While extracting indigo dye the concentration of purified indigo dye may be controlled by adjusting the pH level. Due to the various uses of dyes the adjustment of surface color must be considered. In regard to the change according to different concentrations of reducing agents, it was found that cotton fabrics and ramie fabrics show the highest color difference at 0.4% and 0.3% respectively. As the reduction temperature increases, the color difference increases as well. The maximum color difference was found to appear at $90^{\circ}C$. Cotton fabrics and ramie fabrics showed 70.55 and 67.01 respectively. The color difference increases as the concentration of dyes increases, but at a concentration of 300%, cotton fabrics was found to show 6.22PB in H value using the Munsell color system, containing purple and blue color. The pH of the polygonum dyes extracted through this experiment were adjusted by adding calcium oxide to the experimental water, without directly adding calcium oxide to the liquid polygonum extract. In a refine state, it was mixed with polygonum extract to extract a more refine and highly concentrated indigo dye. When lye and reducing agents are added to extracted indigo dye and sealed for long-term storage, it can be effective and easily used for dyeing.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.23-32
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• 2009

The objective of this study is to investigate the efficacy of leaf powder colorants as substitutes for traditional indigo dyeing. Leaf powder colorants were prepared by hot air($50^{\circ}C$) and room temperanrre($25^{\circ}C$) drying methods from fresh leaves. The presence of indigo in the leaf powder colorants was confirmed by UV/Visible absorption spectra. All the powder colorants showed broad absorption at 602 nm as same as synthetic indigo. Dyeing was done by reduction method with sodium hydrosulfite and sodium hydroxide. Leaf powder colorants produced blue color on silk fabrics, showing similar color to the one dyed traditionally with fresh juice extract. The powder colorants prepared at room temperature drying were more stable for long term storage than that prepared by hot air drying. Thus, the powder colorants prepared by room temperature drying was reduced and dyed in one-step process without sodium hydroxide in the dyebath for further investigate dyeing properties. K/S value of the fabric dyed without sodium hydroxide was much higher than one dyed with sodium hydroxide. Regardless of the addition of sodium hydroxide, rubbing fastness was fairly good showing above 4 rating. Fastness to dry cleaning and light of the fabrics dyed without sodium hydroxide were mote higher than that dyed in alkaline condition.

• Textile Coloration and Finishing
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• v.16 no.2
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• pp.25-33
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• 2004

Melange yams were prepared by varing the ratio of raw cotton dyed with Indigo, Gardenia and Sappan wood colorants, respectively. The antibacterial activity and deodorization on melange yarns were evaluated for bacteria reduction rate and deodorization rate. The bacterial reduction rate on melange yarns was explored with Staphylococcus aureus, Klebsiella pneumoniae. The melange yarns on the ratio of raw cotton dyed with Sappan wood and Indigo showed high Staphylococcus aureus reduction rate of 99% and 90%, regardless of Al-mordanting treatment, but those with Gadenia hardly showed bacteria reduction rate. The melange yarn showed high Klebsiella pneumoniae reduction rate of 99% for Al-mordanting treatment with Sappan wood. The others were poor. The deodorization of 81% and 98∼99% obtained with melange raw sliver and melange sliver dyed with Indigo, Gardenia and Sappan wood colorants, but dyeing did not significantly affect deodorization rate.

• Journal of Fashion Business
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• v.15 no.4
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• pp.144-154
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• 2011

Polygoum tinctoria dye is the one using the method of reducing dyeing, and so is made by the mechanism different from natural dye in general, and the reproductive dye is more difficult because it varies in accordance with manufacturing method and days being manufactured in case of natural indigo dye that has been used traditionally. In addition, overall analysis is short of color changes in accordance with natural dyeing condition and barely none of the research for cellulose system such as cotton in particular. Accordingly, this study tries to research on the natural dyeing method optimal for color development that is desirable in designing and development of natural dyeing as comparing and contemplating the change of dyeing quality and color in accordance with reduction temperature and time, reductant quantity, dyeing temperature and time, NaOH quantity, and dyeing repetition times in order to expand dyeing methods and use variously polygoum tinctoria by improving traditional dyeing methods as well as to establish exact dyeing method of cotton which is a fabric of cellulose system in order to make such polygoum tinctoria quantificated and reproductive. The optimum conditions in the dyeing procedure are as follows: Reducing temperature is $50^{\circ}C$. Added concentration of the reducing agent is $3g/{\ell}$. Reducing time is 30minutes. Dyeing temperature is $30^{\circ}C$. Added concentration of NaOH is $1g/{\ell}$. Dyeing time is 30minutes.