Studies on the Testing Methods for Color Fastness to Perspiration and for Color Fastness to Light and Perspiration for Reactive Dyeings of Cotton Fabries

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On immersing cellophane dyed with reactive Cu-complex azo dyes in aqueous His, the copper atoms of the dye were abstracted the His and the absorption spectra of the dyes were changed with time depending upon the conditions of immersion. The rates of color variations of Cu-complex azo dyes on cotton fabrics were faster than those on cellophane, although the order of the rates of the dyes on both samples were similar to each other.The testing methods for color fastness to light and perspiration including JIS L0888 methods and their improved ones were applied to cotton dyeings by 14 reactive dyes to examine whether or not these methods could assess the potential properties of dyes. The effects of substrate, water, and the pH of aqueous artificial perspiration in which the test fabrics were immersed on the intial and subsequent fading for these dyes were analyzed in terms of their potential properties. On exposure, many dyes on cotton fabrics which are wet and contain some substrate undergo initially oxidative fading from the surface and subsequently reductive one depending upon their potential properties. ATTS and LACT methods distinguished sufficiently the grading of these dyes, while JIS and Mizuno methods did insufficiently.When no His existed on cellulose, Cu-complex azo dyes showed small fading on exposure irrespective of whether they were wet or dry. The color variations of the dyes by immersing aqueous His and/or EDTA were much larger than those by exposure. When His existed on fabrics, His had large effects on fading especially in case of wet fabrics to give large color variation. In some cases, the variations by exposure became larger than those by the immersion. But, the large color variations after exposure were found to be considerably due to the yellowing of cotton fabrics by His, when His was singly used.