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.
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Textile Dyes »
Dyes for Cellulose Fibers
» Direct Dyes
| Dyes for Cellulose Fibers | Dyes for Protein Fibers | Dyes for Synthetic Fibers |
| Azoic or Naphthol Dyes | Bi Functional Dyes | Direct Dyes | Reactive Dyes | Sulphur Dyes | Vat Dyes | ||
What is LightfastnessLight-fastness means the ability of any fibers or
plastic materials to resist the fading or degradation when exposed to
sunlight or to ultraviolet light. In general term, light-fastness is to
be measured by the time duration for which the printed digital image
lasts without fading. |
| » How to solve the wash fastness problem for Direct Dyes |
In most Direct Dyes, the wash fastness quality is poor.
After every dyeing, these dyes bleed a little with every washing. This
results in losing brightness and also damage other clothes which are washed
in the same load. So, there is a process i.e. 'special after treatment' can
be used to solve this problem. For accomplishing this process, a cationic
bulking agent i.e. RETAYNE is used. This agent glues the dyes into the
fibers. This process is used for dyeing fabric with Direct Dyes and these
dyed fabrics are free from bleeding.
| » Disadvantages of Direct Dyes |
- Few Direct Dyes have low light fastness.
- Many Direct Dyes are bland and dull in color.
- Direct Dyes provide duller color than the color provided by the fiber reactive dyes.
- The wash fastness quality is also low.
| » Major types of Direct Dyes |
There are two major types of Direct Dyes:
Cationic Direct Dyes
The main structural features of cationic direct dyes are: (a) the structural single and double bondings are extended. (b) the molecular structure is planar, and (c) positive charges are more than the negative charges.
Anionic Direct Dyes
Anionic Direct Dyes are used for coloring papers, controlling tint and shade and correction of two sided paper color. The main structural features of the Anionic Direct Dyes are: the planar vary from each other, the structural single and double bonds are very much extended, and contains one or more than one sulfonate groups. These sulfonate groups make them soluble in the water.
Cationic Direct Dyes
The main structural features of cationic direct dyes are: (a) the structural single and double bondings are extended. (b) the molecular structure is planar, and (c) positive charges are more than the negative charges.
Anionic Direct Dyes
Anionic Direct Dyes are used for coloring papers, controlling tint and shade and correction of two sided paper color. The main structural features of the Anionic Direct Dyes are: the planar vary from each other, the structural single and double bonds are very much extended, and contains one or more than one sulfonate groups. These sulfonate groups make them soluble in the water.