concentration are presented in Tables 4, 6–9. Table 4 shows that the wash fastness ratings of both non-mordanted and mordanted dyed samples were very poor to poor (1–2), except for ferrous sul- fate mordant, whose rating was fair to good (3–4). The low gray scale rating is caused by the original color of the dyed fabric visually becoming more reddish after the washing test, as indicated by the positive values of a*, except for copper sulfate mordant (Table 5). This drastic color change may be attributed to (a) the ionization of the hydroxyl groups in the dye molecules under the alkaline condition of the standard detergent solution (Räisänen et al., 2002;