Why do Woolen Clothes Shrink?

Why do Woolen Clothes Shrink?

Posted by Team NZNC on 13th Jul 2021

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 (woolen) pyjamas. But with good reason.

It’s durable, comfortable, breathable, water resistant and odour resistant. And most knitwear will last for decades. Which makes it vastly better value than synthetic products that last for decades in the bad way. Wool also happens to be biodegradable.

Of course one of the reasons for the success of wool is how humans have carefully bred the sheep in order to produce the best quality wool. The better the wool, the better the garment.

But for all the careful breeding, quality wool, technology and advanced processes that now go into making incredible ranges of knitwear, the two of the most searched for terms on the internet - when it comes to wool are:

  • ‘why do woolen clothes shrink’ and
  • ‘how to unshrink wool’

For all our genius we still haven’t yet mastered the ability to stop our favourite jerseys from shrinking. So we decided to take matters into our own hands and answer these questions once and for all.

The Cause of Shrinking

For all its incredible properties and natural hardiness, wool can be quite a delicate fibre - especially if mistreated.

It was always assumed that the heat was the root cause of wool shrinking. Although it’s true that the hotter the wool fibre the more relaxed it becomes which can cause felting.

Essentially the fibres weave together and bind together.

This is the process of water felting...but by accident.

This can account for some instances of shrinking but it actually has far more to do with the kind of detergent you’re using.

Assuming you’re reading the care label (because it’s there for a reason) and not setting your washing machine on too high a temperature, using the correct washing detergent should prevent shrinkage.

Most detergents are alkaline based because the majority of garments that go into the majority of washing machines around the world are cotton or synthetic.

Alkaline detergents are more effective at washing these types of fabric. The reason being quite simple - cotton can’t take the punishment. Which is fine, cotton isn’t naturally an insulator. It comes from plants and is grown to protect its seed pods.

It should be a crime if you don’t hand wash with cold water and wool soap per the care label.

The get out of jail card is a machine wash wool cycle on cold.

What is a machine wool cycle?

1. It is a short time span

2. less agitation

3. uses a wool friendly soap not detergent in the right way.

4. put garment in a wash bag.

A machine can agitate so fiercely felting will begin to occur. A wool cycle has less agitation than a normal cycle.

To take more stress out of the risk of wool washing , put the garment in a perforated type cloth bag! Why? Because the little holes the machine has in the drum can see the wool being forced through them! Of course the garment won’t fit through but small areas forced up against a draining spin cycle will try to get through the holes (this is also the start of the felting process.

Another consideration is washing those Merino Work socks inside out occasionally to clear the lint and reduce risk of felting of the terry loop construction! Making the foot all cosy again.

It’s intended purpose was never to be worn or used as an insulating layer for mammalian life. Not so in the case of wool. It’s a different kind of fibre with different properties.

This is why you should use dedicated wool detergent. The chemical composition is tailored to match the unique properties of wool rather than the ‘okay for everything’ alternative that you’ll find on the shelves of your local supermarket.

Wool detergents tend to be PH balanced. They also don’t have any of the ‘bio’ enzymes found in a lot of detergents which can be damaging to the wool.

It should go without saying, but never use bleach. Of any kind. Ever.

You can use softeners but use them sparing. Softeners lubricate the fibres, causing them to shift to the surface. This is one of the causes of pilling.

Of course none of that has anything to do with shrinking, it’s just good wool care.

Lying your garments flat and allowing them to dry naturally will also prevent shrinking. Try to avoid overly hot rooms or in the direct intense sun drying where possible.

Can you Unshrink Wool?

It’s a question we hear a lot.

It’s also something of a controversial topic as there are no shortage of remedies out there that we generally wouldn’t recommend.

Assuming the fibres haven’t been damaged the issue in most cases is felting - the fibres becoming bound together, making the garment shrink.

The key here is to relax the fibres so you can get the garment back to the correct size again.

Using something like hair conditioner in a basin or bath or lukewarm water should give you the give you need without damaging the fibres.

Once the garment is fully saturated gently press out the excess water against the sides of the basin. Do not squeeze or wring the wool, this will only make matters worse.

Then lay garment on a towel and place another over the top. Use the towels to absorb the majority of the water, replacing the towels as needed.

Then it’s just a case of gently reshaping the garment, making sure you work the garment evenly.

This will need doing two or three times as the garment dries.

Finally, once you’re happy, wash the garment again in cold water with wool detergent just to get the hair conditioner out. Again, lay flat to dry. You may need to reshape again, one last time, just in case some of the fibres haven’t quite freed up.

Of course the best way to avoid all the time, effort and heartache of shrinking your knitwear is to (a) buy high quality knitwear, because that does makes a difference. And (b) care for it correctly. Which means not chucking it in the wash with everything else.

Don’t forget knitwear - whatever it may be - is an investment that can last decades. It isn’t a cheap cotton tshirt or a cheap pair of imported novelty socks. They are premium products and that means a premium solution.

The great thing is - beyond reading a label and buying an extra laundry detergent every now and then, it’s a really easy issue to solve.

2 garments we think you might like:

The MKM Ultimate, this garment has the added suede wear patches on the elbow and for those that carry fence posts or just want to look cool its on the shoulders too!

Womens Plain Zip Jacket - A basic for every wardrobe

To view our range of all natural, all NZ knitwear ranges, click here. If you have a question about wool care (or anything else for that matter) get in touch and we’ll be happy to help.