5. Types of cellulosic fiber
• Natural fibers
Natural fibers are textile fibers made from plants
cellulosic (from plants)
(From cotton plants)
From flax stems
Jute (jute stems)
15. At a glance
dyeing of cellulosic fiber with different
Cotton, Rayon, Hemp, Linen, Bamboo etc. Reactive dyes (mostly used)
Cotton, Rayon, Hemp, Linen Vat dyes
Cotton, Rayon, Hemp, Linen Direct dyes
Cotton, Rayon, Hemp, Linen Azo (banned)
16. Direct dyes for cellulosic fiber
• They can be dyed directly on cellulosic fiber.
The effect of electrolytes to the dye liquor
tends to promote exhaustion of direct dyes.
• Cellulosic fiber have a negative charge when
immersed in water, electrolytes reduce the
charge on the fiber surface.
18. Properties of direct dyes
• Soluble in water
• Anionic in nature
• Available in full range of hue
• Poor wash fastness
• Light fastness poor to fairly good
• cheap in price
20. Reactive dyes for cellulosic fiber
• Reactive dyes comprise of a chromophare and
reactive group, they chemically react with the
fiber forming covalent bonds.
Components of reactive dyes :
S= solubilizing group,
B= bridging group,
X= reactive group.
22. The three step exhaust dyeing process
of reactive dyes
1. The initial exhaustion phase,
2. The fixation phase,
3. Post dyeing washing phase.
23. Vat dyes for cellulosic fiber
• Vat dyes are insoluble in water and can not
dye fibers directly. However, they can be made
soluble by reduction in alkaline solution which
allows them to affix to the textile fibers
25. Properties of vat dyes:
1. Vat dyes are natural coloring dyes,
2. Insoluble in water,
3. Large dye stuff molecule,
4. Mostly used on cellulose,
5. Expensive in price,
6. Relatively complicated dyeing method.
27. Basic dyes
• Basic dyes are basically comes from base and
the color is in the base.when acid react with
base, then the color shows. As the color is in
the base the dye is named basic dyes.
28. Properties of basic dyes
1. Brillance and intensity of color,
2. Soluble in alcohol and methylated spirit
3. Are not easily dissolved in water unless care is
4. Some of them are decomposed by boiling water,
5. When treated with alkali it decomposes,
6. water containing alkali or temporary hardness
should not be used,