Why do Woollen Clothes Shrink?

Why do Woollen Clothes Shrink?

Posted by Team NZNC on 13th Jul 2022

Wool is incredible stuff. Uniquely so. There is no other natural fibre that can accomplish the same set of benefits as wool - especially sheep’s wool.

Of course, cashmere and angora are great but sheep’s wool, especially merino blended with Possum Fibre - for us - is the cat’s (woollen) pyjamas. And for good reason!

It’s durable, comfortable, breathable, water / odour resistant and it will last for decades. It’s understandable why many favour wool over any synthetic alternative. To add another benefit to the pile, wool is also biodegradable. Instead of sticking around and causing more landfill like any synthetic fibre.

Of course, much of the reason wool is so popular is because we humans have figured out how to carefully breed sheep in order to produce high quality wool. The better the wool, the better the garment.

Although we have masses of knowledge available to us about woollen clothes, when wool is involved, the two most searched for terms are:

  • ‘why do woollen clothes shrink’
  • ‘how to unshrink wool’

It seems that for all of our ingenuity and genius, we still haven’t figured out how to stop our favourite woollen jumpers from shrinking. Luckily, that is where we come in. If you’ve ever wanted to know why your knits shrink in the wash and how you can stop it from happening, this is the blog for you.

Why do woollen clothes shrink?

If you’ve been in the unfortunate position of pulling your favourite knit out of the wash only to realise it will now only fit someone 10 years your junior. You’ll want to follow along!

For all its incredible properties and natural hardiness, wool is quite a delicate fibre.

The heat and action in the washing machine can cause wool to shrink. Wool fibers are made out of protein scales. Heat and motion cause the scales to grow and rub against one another, which draws the fibres closer together. The wool shrinks more as the fibres get closer together.

In simpler terms, the heat and movement in the washing machine makes woollen fibres grow and the closer they get together, the more the wool will shrink.

It’s a pretty easy mistake to pop your knitwear into the wash without reading the care label. (On most garments you will usually find this on the left, inside the garment as a fabric tag).

Taking a moment to give it a read and find out the correct washing instructions could save you having to pass along your favourite wool jumper to your younger siblings.

Your choice of soap or wool wash could also be playing quite a significant role in shrinking your woollen clothes.

Ideally, you should be using a neutral, mild soap, wool wash or laundry powder. Avoid using heavy-duty or “bio” soaps containing enzymes, or any soaps or powders containing bleaches.

Now, let's assume that you have read the care label, made sure that your washing machine is running on a cold wash and you use the correct laundry powder, you shouldn’t find yourself giving away any of your knits any time soon.

The heat that you choose to wash your knitwear on and the detergent you opt for are the two main reasons why most people shrink their favourite woollen items. So, the next time your knitwear needs a wash, be sure to read the care label and pick yourself up a wool friendly soap.

For a simple, handy guide on how to care for your knitwear at home, check this out on our page.

If I have shrunk my woollen clothes, can I fix it?

I imagine that the likelihood is that if you’re reading this blog, you’ve probably fallen victim to the shrinking of one of your woollen items. Now you understand why it’s happening, I’m sure you’re wondering if there is anything you can do to reverse the shrinkage.

Well, you would be in luck!

Now that you have the ‘why, it’s only right that I teach you how to reverse the shrinkage.

You can do all of the woolly reading available to you but sometimes, mistakes do happen. And if you’re ever in a bind, here are the steps to fix it:

1. Fill your sink or basin with lukewarm water and 1/3 cup of hair conditioner

2. Pop the jumper in and let it soak for about 10 minutes

3. Drain the water out of the sink. When the sink is empty, press the jumper against the sides of the sink to rinse the jumper out, but do not wring it.

4. Put down an absorbent towel, lay the item flat on top of it and lay another towel on top. Press gently to dry the jumper.

5. Stretch the jumper back into its original shape.

6. Keep the item lying flat in a very well ventilated area until dry.


If you want a little bit more information about how to unshrink your clothes, we have a great blog here that will fill you in on all of the information that you need to know.

A basic for every wardrobe

There are added suede wear patches on this garment

Time to give your wool a new lease of a life!

So, there you have it. You now know why your woollen clothes shrink and what you can do about it if it ever happens again.

No more stuffing your old favourites to the back of your wardrobe or passing them on to loved ones. Just you and your knitwear, living happily ever after!

If wool is still on your mind, we have a range of great blogs here that will fill your appetite. Until next time!If you have a question about wool care (or anything else for that matter) get in touch and we’ll be happy to help.

Further Reading: