A study on extraction methods and ultrasound dyeing of natural dyes from dirinaria picta and chrysothrix xanthina lichens / Atiqah Idris

Natural dyes are particularly well known as biodegradable and less pollution contributor as compared to synthetic dyes. Research and production of natural dyes have gained interest due to the growing awareness to safeguard the environment and improve health care. In this study, lichens were selected as the natural dye source for their potential to produce colours on fabrics without any mordants since they are substantive dyes. Dirinaria picta and Chrysothrix xanthina lichens were collected and extracted using boiling water method (BWM), ammonia fermentation method (AFM) and solvent extraction method (SEM). The Dirinaria picta species produced darker and various colour shades as compared to Chrysothrix xanthina. On silk fabric, the shades from Dirinaria picta were dark brown, pale brown, beige, purplish and light yellow while Chrysothrix xanthina exhibited light yellow shade. In the case of cotton, most samples only showed some tinting indicating the absence of dye affinity except for Dirinaria picta extracted by AFM that gave light brown shade. The effect of different extractions and dyeing methods on silk and cotton dyed fabrics were investigated for colour properties and colour fastness to washing, perspiration, rubbing and light. Out of the three extraction methods, AFM produced higher colour strength (K/S) values. The overall colour fastness results for silk fabrics gave ratings from moderate to fairly good (3/4 to 4) and fairly good for cotton. The light fastness results were from 2 to 4 indicating poor to moderate rating.