Natural Dyes for Dyeing Natural Fibres

Abstract

In the first part of this paper an overview of recent work has been provided for general characteristic of natural dyes and their application on natural fibre. It also includes a critical discussion on effects of mordants, methods of extraction and dyeing methods and colour fastness behaviour. Second part of this paper deals with some important R&D studies carried out in our laboratory for production of eco-friendly dyed jute and cotton textiles by applying selective natural dyes on these two fibres with selective mordants after optimal extraction of the natural dyes. Finally, variation in colour parameter and colour fastness properties have also been mentioned with alternative route for improving colour fastness to wash and light. Conventionally H₂O₂ bleached jute and cotton fabrics have been subjected to pre-mordanting with selective single and double mordants using myrobolan (harda) and other mordants (metallic salts) followed by dyeing with aqueous extract of jackfruit wood, Tesu and Manjistha and then studied for their mechanical and dyeing properties. It is observed that the application of 10-20% myrobolan followed by 10-20% of Al₂(SO₄)₃ in sequence have been identified as the most prospective mordanting systems. Colour fastness to washing, rubbing and exposure to sunlight, in general, and dyeing-pH sensitivity, in particular, for selective fibre-mordants- dye systems have also been assessed and compared. Dyeing at pH 11.0 for both the double pre-mordanting systems offers overall good colour fastness properties.