Souring process in the textile

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Souring process in the textile:


The main chemical for the process of scouring is alkali or sodium hydroxide (NaOH). If there is a small amount of alkali in the scoured product, if it is not removed, the subsequent processes will be very difficult. Alkali is alleviated by treating the scouring cloth or with 1 to 2% dilute hydrochloric acid or sulfuric acid at room temperature.

Therefore, the process by which alkali is removed from the fabric processed by dilute hydrochloric acid or dilute sulfuric acid or the alkali is neutralized is called souring.

Souring process in the textile-The necessity of Souring:

Natural fiber contains a variety of waste products such as oils, fats, and waxes. The cloth has to be treated with alkali or soap to remove the waste. Even after cleaning the cloth thoroughly after treatment with alkali, a small amount of alkali remains in it.

It is imperative to remove the alkali, as the remaining alkali reacts with the fabric during subsequent dyeing and printing, causing serious inconvenience to dyeing and printing. Therefore, to remove this small amount of alkali from cloth or yarn, it has to be treated with dilute hydrochloric acid or dilute sulfuric acid. As a result, the following processes are perfect and there is no possibility of unequal dyeing in the dyeing. So in the case of wet processing, the need for souring is immense.

Souring Process:

Natural cellulose fiber cotton is boiled with caustic soda to remove oil, fat, waxes, etc. In modern methods, scouring and bleaching are done simultaneously. Scoured cotton is well washed but retains a small amount of alkali or caustic soda. The alkali is treated with a small amount of dilute hydrochloric acid or sulfuric acid. The remaining alkali becomes neutral when treated with acid.

To souring in a device called Kier, the complete solution of the alkali mixture is first extracted. The cloth is then washed twice, first with hot water and then with cold water, and completely drained out through the output pipe. A 1-2% dilute hydrochloric acid solution is then run in the caravan. The whole cloth is left for 20 to 30 minutes after soaking in dilute acid solution. It neutralizes the alkali by reacting the alkali with the acid. The fabric is then washed with cold water and taken for the next process.

The difference between scouring and souring :

1. The scouring process removes oil, fat, wax, and other wastes from the product.  1. The alkali of the scouring process is eliminated by souring and any kind of waste in the souring process is not removed.  
2. Scouring is usually done in alkali and soap solutions.  2. Souring is done in dilute hydrochloric acid or sulfuric acid solution.  
3. The solution requires heat for boiling.  3. No heat is required, Souring is done at room temperature  
4. Time required for scouring.  4. There is no fixed time in the souring process.  
5. Scouring is done at a certain pH range.  5. Here pH is not required.  

Advantages of Souring:

The benefits of souring are as follows:

1. Souring can be done on easy terms. For example, pH control is not required.

2. Souring can be done at room temperature and in a short time.

 3. Souring is done with a small amount (1-2%) of dilute hydrochloric acid or dilute sulfuric acid.

4. Good results are obtained in subsequent processes of souring cloth. Good results are found especially in dyeing and printing.

5. The souring process provides special assistance in increasing the quality of fabrics in the competitive market.

6. The chances of error in the wet processing of cloth are much less.

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