Classification of Desizing methods
The desizing process of the fabric can be classified into main three categories, as per the chemicals and methods are subcategories.
Desizing methods
A) Hydrolytic methods | B) Oxidation methods | C) Novel methods |
A)Rot steep | A) Chlorine | A) Solvent |
B)Acid steep | B) Chlorite | B) Desizing 2000 |
C) Enzymatic D)Alkali desizing | C)Bromite | C) Low-temperature plasma treatment |
Among hydrolytic desizing processes, alkali designing is discussed below.
Alkali desizing
Alkali solutions are utilized in the industry because acid desizing is a significantly more expensive procedure.
To
hydrolyze starch, use a 2-3 percent solution of an alkali, such as
NaOH. The fabric is squeezed and stored for 4-6 hours after
being padded in the alkali solution.
After that, it's rinsed in hot water thoroughly before being
cleansed in cold water.
Advantages -
1. scouring action is done simultaneously so, does not requires a
separate scouring operation.
2. Process is faster than the rot steep method.
Disadvantage-
2. There is a risk of degradation of the fabric due to local drying as well as alkali.
3. The efficiency of alkali desizing is also very less than acid desizing.
4. Weakening of cotton is possible if proper precautions are not taken.
 |
| Alkali desizing process layout |
Special precautions are taken to avoid fabric contact with air-
Because starch hydrolysis is an exothermic reaction, the temperature of the cloth rises as the reaction progresses, occasionally reaching 50°C. As a result of this rise, we must use caution when using weak mineral acids.
In a closed environment, weak mineral acid at 50°C (in the aforesaid conditions) will not hydrolyze cotton cellulose, and the fabric will not 'tender' as a result of the desizing process.
This precaution must be taken to ensure that the acid does not harm the cloth.
Local evaporation of water from the liquor will occur if the acid-impregnated material is not properly closed, especially in regions that are open to the outside air.
Effect of Higher concentration acid taken or strong acid use-
The fabric's cellulose will be hydrolyzed if the acid concentration is higher or more powerful acids are used.
As a result, the fabric will degrade in random places, causing uneven degradation.
When uneven dying or printing happens, this damage is usually found much later, during the dyeing or printing process.
 |
| Desizing action at the micro level |
Questions -
- What is alkali desizing?
- What are the advantage and disadvantages of alkali desizing?
- What are the precautions that are taken to avoid fabric contact with air?
- What is the side effect of using highly concentrated acid on fabric for desizing?
References
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(N.d.). Textilelearner.net. https://textilelearner.net/flow-chart-of-textile-wet-processing/
Babu, S. (n.d.). Textile Adviser. Textileadvisor.com. from https://www.textileadvisor.com/2021/12/fabric-desizing-process-types-of.html
Desizing. (n.d.). Kemin. from https://www.garmonchemicals.com/en/textile-chemicals/garment-denim-finishing/enzyme-desizing
Landage, S. M. (2022). Biotechnological approaches in desizing of textile materials. In O. L. Shanmugasundaram (Ed.), Applications of Biotechnology for Sustainable Textile Production (pp. 47–73). Elsevier.
Madhu, C. (n.d.). TEXTILE CHEMROSE. Blogspot.com. from https://textilechemrose.blogspot.com/2015/12/desizing.html
Process of cotton Textile Materials desizing. (2013, September 12). Fibre2fashion.com; Fibre2Fashion. https://www.fibre2fashion.com/industry-article/7064/problems-in-desizing-cotton-textile-materials
Trivedi, Y. (2021, May 9). Textile Desizing process. Textilesphere.com. https://www.textilesphere.com/2021/05/desizing-textile.html
Further reading,
Part 2 Desizing process reactions - Hydrolytic and Oxidation method
Part 3 Three chemicals that carried out desizing
Part 4 Rot steep and Acid steep methods for desizing
Part 5 Alkali desizing
Part 6 Hydrolytic desizing
Part 7 Desizing with the help of the Enzymes
Part 8 Continuous desizing process (Winch and J-box)
Part 9 Desizing of polyester-cotton blends
Part 10 Padroll and padsteam desizing
Part 11 Novel desizing
