3.4.7. Colour fastness
The rating of fastness (light, water, washing, and rubbing
fastness) of pre-mordanted and un-mordanted wool fabric dyed
with indicaxanthin dye is shown in Table 3. It was found that
water, washing, and rubbing fastness of un-mordanted woolfabrics
showed considerably good. However, the light fastness of unmordanted
wool fabrics was bad. Generally, it is well known that the
poor lightfastness was a problemfornatural dyes. The lightfastness
of pre-mordanted wool fabrics was significantly found to increase
from rating 3 to rating 4 using MnSO4 and FeSO4, and from rating
3 to rating 5 using KAl (SO4)2 and CoSO4. However, the other mordants
among mordants used in this study did not affect the light
fastness of pre-mordanted fabrics. From these results, it was concluded that mordantsKAl(SO4)2 and CoSO4 were the best mordants to improve the light fastness of wool fabrics.