The influence of after-treatments on dyeability of raw and bleached cotton with curcumin, and visibility of anthotype produced motifs

Abstract

Dyeing of raw and bleached cotton fabrics with a natural dye of curcumin was studied to implement the ancient and environmentally friendly technique of developing photos called anthotype. With the aim of achieving diff erent colours of dyed cotton fabrics, several modifi cations were performed, such as extraction of curcumin in hard and soft water, after-treatments of dyed cotton, i.e. with ferrous sulphate, zinc chloride and silver nitrate, aftertreatment in alkaline bath, and aftertreatment with other natural dyes (blueberry and raspberry). The colour values of dyed samples were determined using a refl ectance spectrophotometer. Colour stability to light was determined by the standard method in Xenotest. It was found that the use of various metal salts, natural dyes, alkalinity and hardness of water infl uenced the colour changes of the substrate. Yellow, red, greenish and brownish colours of fabrics were produced by diff erent treatments. Since the use of metal ions improved the stability of curcumin to light, the motifs produced by anthotype technique were hardly visible. It was found that the natural dye of blueberries and raspberries did not infl uence the light stability, therefore a larger colour contrast between exposed and unexposed areas of the fabric was visible, and consequently good visibility of the motifs was achieved.

Keywords

• cotton
• curcumin
• after-treatment
• motifs
• anthotype