Direct Dyes are commonly used on cotton fibers. These
Dyes are mixed in all purpose dyes along with the Acid Dyes. The color
of Direct dyes on cotton fibers is not bright in respect to other dyes.
The wash fastness of these dyes is not very good. The only advantage of
these dyes is that the light fastness is little more better.
Lightfastness means the resistant capacity against fading in light. But,
this is also in few cases only. One more benefit of using Direct Dyes is
that these can be used in the same dye bath with the Acid Dyes.
If anyone wants to get desired result by mixing Direct Dyes with
unmixed cellulose then he/she will have to take these direct dyes in
their pure form unless the use of these dyes become worthless. It is
preferable to use direct dyes on the cellulose fibers. But if these dyes
are accompanied with 'reserving agents' then these can be also used on
stain silk and wool. But, unfortunately the 'reserving agent' is not
available to home dyers.
Few Direct Dyes, like Direct Orange 39 and Direct Blue 86 are
considered as having very high Lightfastness capacity. These two have a
rating of 6 out of 8.
How
to solve the wash fastness problem for Direct Dyes