Valorization of polyphenol-rich extracts from Oroxylum indicum (L.) kurz outer stem bark as sustainable textile colourants: Comparison concerns selected GOTS 7.0 colour fastness criteria on effects of six mordants and pre-, meta- and post-mordanting techniques on dyeing properties

บทคัดย่อ

The Ban Kham Nang Ok weaving and agricultural community enterprise group in Nikhom Kham Soi District, Mukdahan Province had the main issue of low light colour fastness of cotton yarns dyed with Oroxylum indicum (L.) Kurz. This study examined different mordant conditions to improve the colour fastness of the natural dye and to determine whether the resulting colours met the GOTS 7.0 colour fastness criteria. Greenish brown to khaki were received from those dyeing conditions. From FTIR analysis, it indicated that the bark contains polyphenolic compounds, including flavonoids, hydrolysable tannins, and other phenolic compounds. Pre-mordant copper sulphate, pre-mordant red lime, meta-mordant tamarind, meta-mordant red lime, and pre-mordant iron rust showed top five colour-intensity values respectively.  When light, washing, rubbing, and perspiration fastness tests were considered together, post-mordant tamarind and post-mordant iron rust met the GOTS 7.0 colour fastness criteria. Individual colour fastness assessments showed that the post-mordant processes passed 126 out of 144 test results (87.5%), the meta-mordant processes passed 118 out of 144 tests results (81.9%), while the minimum pre-mordant processes passed 109 out of 144 results (75.67%). Selected mordanting conditions achieved light-fastness grades of 4 (fair) or higher, can improve this key limitation of the natural dyes for cotton. These findings identify practical mordanting routes for improving the fastness performance of naturally dyed textiles and support the development of products that comply with GOTS 7.0 colour fastness performance requirements.