Why do clothes shrink?

It’s a modern day tragedy: you have a favorite piece of clothing that fits you perfectly, but when it comes out of the wash, it shrunk. What happened? what did you do wrong? Well, lets take a look.

There are two types of shrinkage, relaxation shrinkage and progressive shrinkage.

Relaxation shrinkage, mostly common in cotton, takes place due to the way the fabric is manufactured. During construction of new clothes, tension is applied to cotton yarns. This tension is suddenly released between the fibers when they are exposed to heat, whether they are steamed, washed or dried. As a result, the fabric shrinks to its natural size, which happens to not be the size that you tried on at the store [insert crying face]. This type of shrinkage is common in most cotton fabrics, which is why they are expected to shrink in the very first wash.

The other type of shrinkage, called progressive shrinkage, is common in animal fabrics (hair) such as wool, mohair and cashmere. As the name implies, during progressive shrinkage, the clothing shrinks a little more each time it is thrown in the wash. But why does this happen? Like the hair on our head, these animal hairs have scales on them. So when the wool gets wet and warm, the scales on the side tend to stick out. Then as you agitate these and rub the fibers against each other in the wash, they lock together. As you continue to agitate the fibers, they get stuck together more and more and the fabric continues to get thicker and thicker and shorter and shorter.

Man-made fabrics like polyester, will never shrink. The only reason a synthetic fiber will ever shrink is if there is a blend of natural fibers in the fabric. Here is a good way to look at it, the more natural fibers present, the more likely the clothing article will shrink.

In an attempt to debunk some myths, Whirlpool, an appliances company conducted some tests to determine where in the laundry process shrinking takes place. According to their study, it is the hot water from the washer that causes the most shrinking, and not the action of the dryer. In addition, the study found that some shrinking takes place in the dryer not because of the heat of the dryer, but because of the spinning action of the dryer.

What do you think? Do you like this? How about a question for next week’s blog.

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