Sunday, 31 January 2010

FAQ about Mercerization



This Article written in early 1900s is a superb treatise on everything about Mercerization:

Here is a list of FAQ that this articles seeks to clarify:

1. Why Mercerization ?

Mercerization was evolved to get over the limitation of silk. It is the high price of silk and low production. On the other hand, a product was needed which could imitate the high lustre, steel-like strength, its attractive smoothness and softness, its elasticity and and its quality of taking the most delicate tints and shades in the dyeing process.

2. What is Mercerization

Mercerization is a process applied to cotton yarn or fabrics which gives to the cotton fiber a silk-like luster, greater strength than ordinary cotton and a greater affinity for dyes.

3. How it is done

The cotton is soaked in strong caustic soda or caustic potash solution for a few moments under stretch and then washing in pure water to remove the caustic.

4. What happens to the structure of cotton during Mercerization

In natural condition the cotton fiber is a flat, twisted, ribbon-like filament. When immersed in caustic solution it swells out and takes on a round and a hair like appearance, and becomes plump instead of flat.

5. What happens to the chemical structure of cotton during Mercerization

The cellulose is changed into hydro-cellulose or cellulose-hydrate.

6. Why mercerized cotton takes dyes so quickly. 

Cellulose cannot be dyed so easily. Hydro-cellulose on the other hand, absorbs almost any kind of dye readily. Mercerised cotton takes dyes so fast, that chemicals are added in the dye bath to check the process in order that the dyes may not enter so rapidly as to render the shading uneven.

7. What is role of stretch during mercerisation.

Stretch causes the luster, the more the stretch the more the lustre. However, after a certain point, the stretch causes a decrease in strength. 

8. How mercerization is done actually ? What are the chemicals added and other process parameters.

9. Apart from Caustic Soda, what other chemicals can be used for Mercerisation, what are their limitations. 

10. Why sometimes Carbon disulphide is added in mercerisation. 

11. Should bleaching be done before or after mercerisation

12. What pre-processes ensure better luster in Mercerisation processes

Please refer to the article.

13. What type of Cottons are suitable for Mercerisation

Longer cottons are more suited to get as much natural luster as possible. Similarly combed cotton lend themselves better to Mercerisation than carded cottons. 

14. What is part Mercerisation. How it is used in produces various fabrics.

Taking a cotton blend, and then mercerising will produce an effect called as crepon effect. Similarly, mercerisation can be used to produce seersucker effect by Mercerising only certain stripes on the warp direction by covering the rest of the cloth by suitable means.

15. How to identify Mercerised Cotton

(This method has not been tried by me. Please take all precautions including consultation from a chemical scientist before attempting)


Mercerized cotton may be determined as follows: A solution is prepared by dissolving 140 gms of potassium iodide in about 475 ml of water. To this solution add 30-60gms of iodine, and mix with another solution made by dissolving 850 gms of zinc chloride in 350 gms of water. The cloth sample should first be soaked in water, immersed in this prepared solution for three minutes, and then rinsed in water. Mercerized cotton will have a deep blue color, while unmercerized cotton will wash out white. The blue of this solution on mercerized cotton will show through quite heavy dyes.

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