Lightfastness properties of leathers tanned with various vegetable tannins

The color changes of bovine leathers, tanned with commonly used hydrolysable and condensed vegetable tannins, were measured colorimetrically as a function of prolonged irradiation with Xenon test light. The results showed that hydrolysable and condensed tannins exhibited differences in their light fastnesses. The color change of hydrolysable tannins under the effect of light was considerably low when compared to the condensed tannins. Gambier and quebracho tannins, among the condensed tannins, exhibited a rapid color change in the direction of red and yellow, while mimosa showed a slower color shift. Tara, among the hydrolysable tannins, exhibited a slower color shift than the others. At the end of 24 hours, the color changes, observed as darkening in all the tannin groups reached a maximum point after which color lightening was observed with extended time.