Fastness of dyestuff solution to sun light

Abstract

To study light fastness of dyestuffs contained in cosmetic liquid, trichromatic coefficients of aqueous or alcoholic solutions containing dyestuff (s) popularly used for cosmetic ingredients were tested by their exposure to sun light for 15 dayes and 30 days, and were plotted on the chromaticity diagram.
1. Chemical structure of a dyestuff has a dominant infuence on the fastness to sunlight.
2. The sort of acid od alkali is found to affect the sunlight fastness of dyestuff more than pH value of the solution.
3. Each perfume shows a different effect on the sun-light fastness of dyestuff.
4. Synergistic effect of perfume and acid or alkali is observed.