electrostatic repulsion between the anionic colorants and the pro- tein fibers occurs, which leads to a decrease in the dye uptake.
Tables 1–3 show the color values of the silk fabric dyed with mangrove bark extract dye solution. The K/S values increased with an increase of dye concentration. The mordant activity sequence for the pre-mordanting method was CuSO4 > FeSO4 > without mordant > AlK(SO4 )2 > SnCl2 and CuSO4 > without mor- dant > FeSO4 > AlK(SO4 )2 > SnCl2 for the meta-mordanting. In the post-mordanting, CuSO4 > FeSO4 > AlK(SO4 )2 > SnCl2 > without mordant was observed. In all cases, the copper sulfate mordant yielded the best dyeing results.
Copper sulfate and ferrous sulfate mordants are well known for their ability to form coordination complexes and to readily chelate with the dye. As the coordination numbers of copper sulfate and ferrous sulfate are 4 and 6, respectively, some coordination sites remain unoccupied when they interact with the fiber. Functional groups such as amino and carboxylic acid on the fiber can occupy