4. Conclusions
The use of hydrolyzed collagen in the dyeing is a novel concept. Even though the results are not promising in the case of cotton, there is a possibility of dyeing without salt, where the hydrolyzed collagen plays the role of salt. Good results are obtained in the dyeing of leather where the synergistic effect of hydrolyzed collagen was evident. Both cotton and leather behave differently towards the hydrolyzed collagen at various pHs. Depending on the pH, the hydrolyzed collagen can improve or reduce the affinity of dyes onto the substrate. The residual bath dyeing process of cotton has not given good results, but it is easy to reuse unlike conventional baths containing salt. On the other hand, dyeing process with residual bath could be used for developing a range of lighter shades on the fabric.