Vat dyeing process

Steps to color the cotton fibers with vat colors


Use the steps given below to color the cotton fibers with weight color

1. Reduction
2. Dyeing
3. Oxidation
4. Heat saponification  (Soap at the boil)

Reduction

In this process, weights bring the colors to a soluble state. For this, add the required amount of sodium hydroxide (NOH) color. After that, mixing the reducing agent for the deficiency and increasing the temperature. Most sodium diethoyanite (NA2S2O4), which is known as sodium hydrosulphite or hydro, is used for its process.
The table below is given the method of uptake weight colors.


Vat dyeing process


Dyeing

The scratched material is dyed in the dyeing machine and the temperature increases (60 ° C) (80Fo140 ° F) depending on the type of color depending on the type of color. Ranges are up to the time according to the requirement. As shown in the table • After this, add salt as per requirement.


Oxidation

 Prior to oxidation, the material is washed thoroughly, which is why NaOH and the dehydration chemicals are well drained. Potassium uses dichromate for oxidation. Nowadays Potassium uses hydrogen peroxide instead of Dichromate.


Hot saponification  (Soap at the Boil)

 In this process, the dyed fabrics are thoroughly washed with boiling water of soap so that the color of the cloth does not turn out.
Dyeing in a character (Standing Bath Dyeing):
Because color is not absorbed by the color of the color, so to reduce the cost of coloring, a character dyeing (standing bath) is used in medium and dark shades, especially in the color of black shed. This method should be used to paint only one shade in many lots and dyeing with one color or two or more colors (two or more colors should not be mixed).

In this method, after coloring, the colors and chemicals that survive in the water do not do any harm, they use another lot in the color dyeing.

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