Fastness
Wash-fastness (WF) and lightfastness
(LF) results of the dyed fabrics
with and without chitosan treatment are
indicated in Table 5. The dyed fabric
treated with chitosan improved both the
light-fastness by one unit on the standard
blue wool scale and wash-fastness by one
unit on the standard grey scale compared
with the dyed fabric without chitosan. In
addition, the results indicate that the use
of mordants also improved the wash fastness
and light-fastness of the dyed
fabrics in some cases, depending on the
mordanting techniques used. For washfastness
of both treated and untreated
chitosan dyed fabrics, the improvement in
wash-fastness was greatest with postmordanting.
This may be due to better
fixing of dye onto the fiber by using the
post-mordanting method and there were
fewer dye molecules for fixing than those
in the other two methods. The
improvement in light-fastness was
maximized with meta-mordanting. This
may be due to the greater complexforming
ability of the metal ions with dye
molecules than occurs in the other
processes.