Wool fabric dyeing by acid dye

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Wool fabric dyeing by acid dye:

There are 3 ways to dye wool the acid dye. ie

A) Application of strong acid on wool.

B) Application of weak acid on wool.

C) Application of neutral acid on wool.

A) Application of strong acid on wool:

In this method, all the waste has to be removed by scouring well to dye the woolen product. https://bdfabric.com/acid-dyes-definition-introduction-properties/

Wool fabric dyeing-Recipe:

 Dyestuff → 2%

 Sulfuric acid → 2%

Salt (Na2SO4, 10H2O) → 10%

Water → 20 times

Temperature → 100°C

Time → 1 hour

Dyeing process:

For strong acid dyes, it is necessary to maintain a strong acetic condition in the dye bath. In the presence of salt, the dyestuff is first mixed with sulfuric acid to form a paste and the dye solution is made. In another dye bath, water is taken 20 times the weight of the product. The dyestuff is then thoroughly chopped and applied to the dye bath. The temperature of the bath is then raised to 60°C and the required salt is added.

Wool fabric dyeing by the acid dye. The wet wool is then taken to the bath and aimed at the dye liqueur to penetrate well before it dries. The wool is boiled at a temperature boiling for 10 to 15 minutes and the product is carefully boiled for 45 minutes. During this time the product absorbs the dye. At the end of dyeing, the wool is thoroughly washed and soothed by ammonia. Then it is washed in soapy water for 10-15 minutes and boiled. Finally washed with cold water.


1) Wool is more sensitive to felting, so be very careful not to move the product too much.

2) Wool is dyed with strong acid at high temperatures, so you have to be careful.

3) Since the process is done in an acid medium, there is a possibility of some acid remaining at the end of dyeing, which causes damage to the fabric. So it has to be alleviated with the help of alkali.

4) Hydrochloric acid or nitric acid cannot be used during dyeing. Because HCl produces fewer ions, HNO3More reactive and can produce H+. Moreover, HNO3 oxidizes the wool.

Wool Fabric

B) Application of weak acid on wool:

Weak acid or salt-forming acids are used when using weak acid dyes.

Wool fabric dyeing-Recipe:

Die stuff → 2%

Acetic acid → 3%

Dispersing agent → 0.2%

Water → 20 times

Temperature → 60°C – 90°C

Time → 1 hour

In some cases 0.5 – 1% H2SO4 is used.

Dyeing process:

The paste is made by dispersing the agent with dyestuff in the dye bath. Later it is dissolved well by adding 10 times the water of dyestuff. Then in another bath with 20 times water put a damp cloth in it and this dye solution is added. The fabric is then dyed for 20 to 30 minutes at a temperature of 60°C to 90°C. And then the wool fabric is washed with cold water.

C) Application of neutral acid on wool:

First, the dye is applied in a neutral bath. Ammonium sulfate is used there. When this salt is heated for a long time, it produces a little acetic medium, which helps in the digestion of dyestuff.

Wool fabric dyeing-Recipe:

Dyestuff → 2%

Dispersing Agent → 01 – 0.2%

Ammonium sulfate → 3 – 4%

Water → 40 times

Temperature → 60°C to 100°C

Time → 45 to 60 minutes.

Dyeing process:

First, the dyestuff is made into a paste with the help of a dispersing agent (T. R oil) and it is dissolved well in hot water. In another dye bath, the first part of the dissolved dyestuff is sifted with water 40 times the weight of the product. The product is then dyed at 80°C for 15 to 20 minutes.

Now the product is taken out of the bath and the 2nd part of the dye and ammonium sulfate is added and the temperature is gradually raised to 90°C to enter the product and the dyeing is done for another 15-20 minutes. The product is taken out of the dye bath again, 3rd part of the dye is added and the dyeing is done by raising the temperature to boil for another 15-20 minutes. At the end of dyeing, the product is taken out of the bath and washed thoroughly.

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