Why Do Clothes Shrink in the Wash?

Ever get some new clothes and then throw it in the wash–only to remember once it’s too late that those clothes will probably shrink inside the washing machine? Or you never considered shrinkage a possibility in the first place, and then pulled everything out of the dryer and realized your mistake as soon as you realized your sweater had probably now just become a crop-top. So why do clothes shrink in the wash?

There’s not a single cause

There are a handful of different mechanisms that can shrink your clothes when you stuff them into your laundry machine or dryer. It largely depends on what your clothes are made of, but the most common shrinking garments are things made of wool. The reason why wool garments are so prone to shrinking is because they’re made of animal hair/fur. Hair generally shrinks in water, because your hair is kind of “scaly” structurally. When water gets into hair, it is absorbed and the fibers collapse in on themselves This causes hair to lose some of its volume (this loss of volume can be up to 75% until it dries again). Because of the structure of each fiber, this type of shrinkage (called felting) only occurs with animal hairs.

Alternatively, your clothes can shrink because they’re relaxed. Just like you, on the couch. Woven yarn is often put under tension before it’s turned into something, you might see this called warping. As you might guess from the word “warp,” this isn’t something the fabric particularly enjoys. When wet, the woven fabric relaxes, and goes back to a less tense form that also ends up being smaller. 

What about the dryer?

So far we’ve been blaming the washing machine for shrinking our clothes. But what about the second machine; the one that dries all the clothes? 

When you throw your clothes in the washer or dryer, you’ll notice that there’s a lot of… Spinning. Depending on your machine, sometimes it sounds kind of aggressive. That’s because the machine is literally beating the dirt out of your clothes–it’s why your dryer collects lint. Sidebar: empty your lint trap. Especially if it’s a shared dryer.

Anyway, when your dryer is beating the crap out of your clothes (literally), it also softens the fibers and tears them from your clothes. When this happens your clothes are both softened and compressed–meaning the fibers that are left end up closer together. That’s also known as “your clothes get smaller over time”.

Some fabrics, like cotton or wool, have natural moisture content. When it gets too hot, these fabrics can drop below their natural moisture content, which can result in shrinkage for your clothes in the same way that raisins are smaller, dry grapes. 

See if you can do this fabric word ladder here.