There are two main reasons why mercerized cotton clothes become softer the more they are washed.
First of all, mercerized cotton is a fabric made of mercerized cotton yarn, and its softness characteristics are closely related to the structure and fiber properties of the yarn. Mercerized cotton yarn is blended from longer cotton fibers and mercerized fibers. The addition of mercerized fibers makes the yarn softer. When we wash mercerized cotton clothes, the friction in the washing machine will make the contact between fibers closer and the gaps between fibers reduced, making the clothes softer. At the same time, during the washing process, the action of water flow and detergent will remove some residual impurities and hard particles at the fiber boundaries, reducing the surface roughness of the clothes and increasing the softness.
Secondly, the local heating and cooling effects during the washing process also help mercerized cotton clothes become softer. During the washing and rinsing process, the temperature of the hot water causes the fibers to expand slightly, and after rinsing, the cooling process causes the fibers to shrink. This cycle of thermal expansion and contraction helps to open some gaps in the fiber structure, further increasing the softness of the clothing.
To sum up, the reason why mercerized cotton clothes become softer as they are washed is mainly because the friction during the washing process tightens the contact between fibers and removes impurities and Hard particles, while the thermal expansion and contraction characteristics also help to open the gaps between fibers, making the clothes softer and more comfortable.
