GATE (TF) Textile 2012 Question Paper Solution | GATE/2012/TF/45

Question 45 (Textile Engineering & Fibre Science)

Consider the following Assertion [a] and Reason [r]

[a] In the case of dyeing of cotton with reactive dyes, formation of hydrolyzed dye is a major problem.

[r] In an alkaline medium, the reactive dye reacts with the hydroxyl groups irrespective of whether these are from cellulose or water.

Determine the correctness or otherwise of the above Assertion [a] and Reason [r]

(A)[a] is right [r] is wrong
(B)[a] is right [r] is right
(C)[a] is wrong [r] is right
(D)[a] is wrong [r] is wrong
Answer / Solution
[Show Answer]

Option A

Frequently Asked Questions | FAQs

How do you dye cotton with reactive dye? |What are the steps of reactive dyeing? | How do you use fibre reactive dye on cotton?

Reactive dyes are the most commonly used dyes for cotton because they chemically bond with the fiber, resulting in a permanent color that is resistant to fading and washing. Here are the steps to dye cotton with reactive dye:
1.Reactive dye
2.Soda ash
4.Cotton fabric
5.Rubber gloves
6.Plastic bucket or container
7.Stirring stick
8.Measuring cup
1.Prepare the dye bath by filling a plastic container or bucket with hot water. The water should be at least twice the volume of the fabric you are dyeing.
2.Add the recommended amount of salt to the water. Salt helps the dye to penetrate the fabric evenly.
3.Dissolve the recommended amount of soda ash in a separate container of hot water. Soda ash is an alkaline chemical that helps the dye to bond with the cotton fibers.
4.Add the dissolved soda ash to the dye bath and stir well.
5.Wearing rubber gloves, wet the cotton fabric in warm water and wring out the excess water.
6.Add the wet cotton fabric to the dye bath, making sure it is fully submerged.
7.Stir the fabric in the dye bath regularly for the first 10-15 minutes to ensure even dye distribution.
8.Let the fabric soak in the dye bath for at least 30 minutes, or longer for deeper colors.
9.Remove the fabric from the dye bath and rinse it thoroughly in warm water until the water runs clear.
10.Wash the fabric in hot water with a mild detergent to remove any remaining dye particles.
11.Hang the fabric to dry away from direct sunlight.
Note: Follow the dye manufacturer’s instructions for specific dye quantities, dyeing times, and washing instructions. Always wear gloves when working with reactive dyes, as they can be harmful to skin and clothing.

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