A Training and Research Program in the Field of Instrumental Color Control for Textiles

摘要

The phenomenon of non-additivity of spectral absorbance values was explored for a selected group of direct azo dyestuffs. Whereas previous investigations have been restricted to studies of a single dye which usually does not obey Beer's law or for dye mixtures which are nonadditive in aqueous solutions, the present work examined non-additivity in water solutions and in solutions containing water and a few polar organic solvents. Mixtures composed of two dyes were made and the absorbance of the mixture was compared to that which would be expected based on the absorbance values of the individual dyestuff in the same medium. Differences between the predicted and actual absorbances were found to be most marked in water solutions with less deviation as more and more organic solvent was introduced. The solvents used were ethylene glycol, methyl alcohol, ethyl alcohol, dimethyl sulfoxide and formamide. Although some of the solvents were effective in reducing or eliminating non-additivity, it was not possible to establish any clear pattern of behavior for each of the dyestuffs. For this reason it is concluded that this approach to the problem is not practical, and should not be pursued further. (Author)