Spectrum of colors from reseda luteola and other natural yellow dyes

Yellow dyes have always been used from ancient times and have been a color of marking festivity. Most of the yellow dyes are flavonoids which are not stable to UV radiation. The dyed fabric shows very poor wash and light fastnesses. In our quest for a stable yellow dye we started exploring all the possible sources of yellow natural dyes ranging from Curcuma rhizome, Eucalyptus barck Super Critical Fluid Extract (SCFE), Gaillardia flower, Thevetia peruviana flower, Tegetus flower, Punica granatum fruit epicarp, Cassia fistula flower, Cosmos sulphuerus flower, Carthamus flower and Reseda luteola flower, stem and leaves extracts. Since a lot of work had already been done for the identification of colorant in Reseda extract, some very pertinent questions arose to understand the mode of attachment of this colorant molecule on the fabric for stable dye adherence and unusual good fastness properties. Owing to its good thermal stability, the colorant can be extracted easily with water at alkaline pH or even with methanol: water mixtures.