Tamarind seed coat tannin was extracted and its tannin class was determined. The extracted tannin was employed as a natural mordant alone and in combination with metal mordant namely copper sulphate for cotton, wool and silk fabrics and dyed using natural dyes namely turmeric and pomegranate rind. The colour strength, colour coordinates, wash and light fastness were evaluated and compared for all the three fabrics with and without mordanting. The pre-mordanted fabrics on dyeing gave better colour strength, wash and light fastness than those dyeing obtained without mordanting. The total phenolic content of the extract was calculated and minimum inhibition concentration was 1% against both the Staphylococcus aureus and Escherichia coli bacteria. The mordanted and dyed fabrics resulted in good antibacterial activity up to 20 washes, when natural mordant was used along with 0.5% and 1% copper sulphate mordant and dyed with natural dyes.

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Although a lot of antibacterial finishes are available for cotton, the user safety and durability of the finish are always the important issues. Some of the natural dyes are known to possess antibacterial properties; however, most of them are nonsubstantive. Hence, they are used in conjunction with eco-friendly natural mordants. Although metallic mordants are effective, they are environmentally pollutants, hence not desirable. In the current work, the novel natural mordant like chitosan with different concentrations (10% and 20% of weight of fiber) was applied on cotton and fabric was printed with natural dyes such as catechu, turmeric, and marigold using screen printing method. All the three dyes were used in powder form in print paste with different concentrations (1%, 5%, and 10%) and guar gum was used as thickener. The printed samples using chitosan as a mordant showed the equivalent color values to that of prints obtained using alum as a mordant. The printed fabric showed excellent antibacterial activity against both gram-positive and gram-negative bacteria. The method may be considered suitable for eco-friendly printing and antibacterial finishing of textile materials.

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