Screening of Vegetal Dyes for Wool Dyeing: Selection of Feasible Alternatives for Industrial Applications

Although there are many studies on dyeing of wool fibers with natural dyes, it is noteworthy that the studies generally consist of evaluating the color and fastness values by dyeing with selected plants and mordants, rather than ensuring that natural dyes are industrially applicable. This study aims to find out whether or not there is any plant that can give good fastness values on wool without using mordant by examining 50 different plants. Thus, plants that gave yellow, red, and blue colors with good fastness values were determined without using mordant. Accordingly, safflower for yellow color, quince leaf for reddish color (dried rose color), and ratanjot for grayish-blue color gave the best results for trichromatic dyeing. Actually, red and blue colors can be obtained successively with madder and indigo, respectively. However, indigo requires a special vatting process, which prevents its usage in the same bath with yellow and red dyes. For this reason, ratanjot can be an alternative for bluish color since it can be applied with yellow and red dyes in a single bath. If madder is used for red when ratanjot and safflower are used for blueish and yellow colors, respectively, an imbalance will occur in trichromatic dyeings due to high color yield of madder. To eliminate this drawback, it was observed that quince leaf rather than madder would be more suitable for trichromatic dyeings. Studies have shown that the ratanjot is a plant that can give bluish color without the need for the vatting process, and thus, the problem of trichromatic dyeing in a single bath has been eliminated. It is assumed that natural dyes should also be available in powder form just like synthetic dyes for obtaining standard production. For this reason, the obtained plant extracts were converted into powder dyes. Finally, color yield and fastness properties were examined by dyeing with powder dyes in different depths. Moreover, it was determined that pomegranate peel, madder, and indigo could be used for bright yellow, bright red, and bright blue colors, respectively, but they were not suitable for dyeing in a single bath. © 2023, The Author(s), under exclusive licence to the Korean Fiber Society.