A new approach for natural dyeing and functional finishing of cotton cellulose

A new approach for upgrading the dyeing properties of cotton knits with natural dyes as well as to enhance both the UV-protection and antimicrobial functions of the obtained dyeings was investigated. Factors affecting the dyeing and multifunctional properties of the treated substrates such as fabric structure, type and concentration of mordant, kind and percent of natural dye extract as well as dyeing regime were studied. In situ deposition of the mordant as a metal oxide onto and/or within the fabric structure followed by dyeing results in a dramatic improvement in the color strength as well as the fastness properties, in addition to an outstanding enhancement in both the UV-protection, against the harmful UV-radiation and the antibacterial activity against the hazardous G+ve and G-ve bacteria. The extent of improvement in the aforementioned properties follows the descending order: pre-mordanting followed by dyeing > dyeing only > none, and is determined by type and content of metal, physical state/chemical structure as well as extent of dye interaction and fixation, along with the fabric construction. The UV-protection properties as well as the antibacterial activities of the obtained dyeings are maintained even after 20 washing cycles. (C) 2010 Elsevier Ltd. All rights reserved.