What is Mercerization?
Mercerization is a unique textile finishing process that involves treating cotton or other cellulosic fibers with a strong alkali solution under tension. This process improves the luster, strength, and affinity for dyes of the fibers, resulting in a smoother and more even surface. By undergoing mercerization, cotton fibers are transformed into high-quality, luxurious textiles, making it a popular choice for clothing and home furnishings.
History of Mercerization:
During the 12th century, the concept of mercerization was not yet known. However, cotton fabric was still produced through labor-intensive methods, which involved handpicking cotton fibers, spinning them into yarn, and weaving the yarn into fabric. The fabric produced through these methods was not as strong, lustrous, or colorfast as the mercerized cotton fabric we know today. Mercerization was first discovered by a British chemist named John Mercer in 1844.
Steps of Mercerization:
The modern mercerization process involves several steps, which is outlined below:
Step-01: Preparation of the fabric
The cotton fabric is first scoured properly, which involves washing it in hot water and the treatment with soap and other chemicals to remove any impurities or dirt from the fibers. It is then treated with a solution of sodium hydroxide, which causes the fibers to swell and become more receptive to subsequent treatment.
Step-02: Mercerization
The treated fabric is then passed through a series of rollers while being held under tension. It is then immersed in a bath of sodium hydroxide, which causes the fibers to swell further and become more uniform in shape. This process also removes any natural impurities in the cotton fibers.
Step-03: Washing
After the mercerization process is complete, the fabric is washed thoroughly to remove any residual sodium hydroxide. This is done to prevent any damage or discoloration of the fabric.
Step-04: Neutralization
The fabric is then immersed in an acidic solution to neutralize the residual alkalinity and stabilize the fabric.
Step-05: Drying
The mercerized cotton fabric is then dried properly to remove water from the fabric. Then the fabric is ready for next process.
Recipe for Mercerization Process:
- Sodium hydroxide (NaOH) or caustic soda: 20 grams
- Water: 80 ml
Preparation of Liquor:
- Add 20 grams of sodium hydroxide (NaOH) or caustic soda to 80 ml of water in a glass beaker.
- Stir the mixture until the sodium hydroxide is fully dissolved.
- The liquor is now ready to be used for mercerization of cotton or other cellulosic fibers.
Factors of Mercerization:
A. Suitable Temperature
Mercerization process is typically carried out at room temperature, as higher temperatures can cause the fibers to break down or dissolve in the alkali solution, leading to irreparable damage. On the other hand, lower temperatures may result in incomplete mercerization and a lower quality end product.
The temperature suitable for mercerization process can vary depending on the specific fibers and desired outcomes, but generally, a temperature range of 18-25°C (64-77°F) is recommended for best results.
It is important to note that the temperature and duration of the mercerization process can impact the final properties of the fibers, such as their strength, absorbency, and affinity for dyes. Therefore, it is crucial to carefully control the temperature and timing of the process to achieve the desired results.
B. Impact of Tension:
Tension plays a critical role in the mercerization process of textiles. When cotton or other cellulosic fibers are immersed in a strong alkali solution, they swell and become highly reactive to the solution. By applying tension to the fibers during the mercerization process, the fibers are stretched and aligned in the direction of the applied force.
The tension applied to the fibers helps to improve their luster, strength, and overall quality. The fibers become more compact and aligned, resulting in a smoother and more even surface. Additionally, tension can help to prevent the fibers from shrinking or losing their shape during the process. The degree of tension applied during mercerization can impact the final properties of the fibers.
Conclusion:
Mercerization process improves strength and durability by increasing cross-linking between the fibers. The process also gives the fabric a lustrous appearance, making it more attractive and easier to dye. Overall, mercerization is an important process in the textile industry, and it has contributed to the production of high-quality cotton fabrics and yarns. With its ability to enhance the appearance, durability, and comfort of cotton products, mercerization has become a staple in the textile manufacturing process.
Working as head of the dept. of Wet Process Engineering at Textile Engineering College, Zorargonj, Chattogram. He is also CEO at TEC Media and advisor at Textile Engineers Club. He hosts textile related online program ‘TEC Show’.
