Journal Textile Coloration and Finishing Year / Vol., Issue, Month 2021 / V.33,no.4,Dec Title Natural Indigo Dyeing of Hanji Fabric using Baker’s Yeast : Effect of Yeast Concentration and Repeat Dyeing Authors Kyunghee Son*, Younsook Shin, and Dong Il Yoo1 Institution/Affiliations Chonnam National University Pages/Total page pp.191 ~ 201 / 11 Language Korean Abstract In this study, an eco-friendly indigo reduction system(scale up reduction, use of buffer solution, and pH control) using baker’s yeast(Saccharomyces cerevisiae) was applied for natural indigo(Polygonum tinctorium) dyeing of Hanji fabric and Hanji-mixture fabric( Hanji/Cotton, Hanji/Silk). The effect of concentration of baker’s yeast, repeat dyeing, and bath reuse was investigated in terms of dye uptake indicating reduction power. And the oxidation-reduction potential(ORP) was monitored. We also evaluated color properties and colorfastness according to the color strength. The yeast concentration did not significantly affect the maximum reduction power. However, the highest yeast concentration was effective in improving the initial dye uptake, and its the reduction retention power was the most excellent. Even on the last reduction day, the effect of increasing the dye uptake by repeat dyeing was observed. And it was confirmed that the reduction bath could be reused for up to 30 days by supplementing yeast at the end of reduction. For all the fabrics used, deeper and darker PB color were obtained by repeat dyeing. As dyeing was repeated, purplish tint got stronger on the Hanji/Silk fabric compared to other fabrics. Regardless of the composition of Hanji fabrics and color strength, washing and dry cleaning fastness were relatively good with above rating 4-5, and fastness to rubbing and light were acceptable with a rating 3-4 ~ 4-5. The eco-friendly natural indigo dyeing process using niram and baker’s yeast would offer global marketability and diversity of Hanji product as a sustainable high value-added material. Keywords hanji fabric, concentration of baker’s yeast(Saccharomyces cerevisiae), repeat dyeing, color strength, colorfastness, sustainable Download   Reference http://koreascience.or.kr/journal/OSGGBT.page?&lang=ko