How to Tell If Yarn is Wool

When you have been knitting or crocheting long enough, you are eventually bound to come across some leftover yarn without a label.

Whether it is your own scrap yarn from previous projects or something that was gifted to you—trying to figure out the material of yarn without a label is not always easy.

If you are trying to figure out if leftover yarn is wool or a synthetic material like acrylic, there are some things you can look for in the yarn to help give you a clue.

In this guide, I'm going to cover some different things you can do to tell if your yarn is wool or not.


The texture of the yarn can give some indication on whether not it is wool.

Wool yarn tends to be soft and hairy.

Feel the yarn and inspect a strand of it. If it's soft and hairy—it could be wool.

You cannot use texture alone to tell you, however it is a good starting point.

There are a lot of synthetic blends like acrylic that can look and feel similar to wool, so judging by just texture alone won't give you a definitive answer.

If you have a yarn that you know is wool, you can also compare it to the unlabeled yarn to see how similar they are.

To be more certain your yarn is wool, you may have to perform one of the tests that we cover in the next sections.

Burn Test

One way to help you figure out whether a yarn is wool or acrylic is to do a burn test.

For a burn test we are going to burn a strand of yarn and pay attention to how it burns. 

Here is how it's done:

  1. Cut a small strand of yarn from the yarn that you want to test (make sure its long enough that you won't burn yourself!)
  2. Try to light one end of the cut yarn on fire (make sure to do this in a safe area)

After you've tried to light the mystery yarn on fire, pay attention to how it burns.

These will indicate that the yarn might be wool:

  • If the yarn doesn't start on fire easily
  • Smells like burning hair
  • If the end of the yarn becomes charred

If the yarn is synthetic like acrylic, you may notice this after the yarn is burned:

  • The yarn melts
  • Smells like burning plastic or chemicals

Your yarn also may be made from a plant fiber and be neither wool or synthetic. 

If it smells like burning paper after the burn test, it might be made from a plant fiber.

Smell Test

If you prefer a simpler test without having to start a fire, you can always try the smell test.

This is probably the most simple test to do.

For this one, just take a small piece of yarn and get it wet. Hot water is better.

Yarn made from animal fiber like wool will smell like an animal when its wet—particularly when it is hot and wet. 

If your yarn smells like a sheep or a wet dog than it's made from animal fiber, so it could very well be will.

If you don't notice any smell, it is probably not wool.

Bleach Test

A bleach test is another good way to figure out if your yarn is wool or not.

Bleach dissolves protein, so we can use to bleach to see if there are protein fibers in our yarn. This could mean it's made from an animal fiber like wool

If you are going to do this test, make sure it's done in a safe well ventilated area where pets or children wouldn't have access.

Here are the steps to do a bleach test on your yarn:

  • Start by pouring bleach in a glass or heavy plastic dish
  • Cut a piece of yarn and place it into the dish
  • Use a small tweezers or something similar to move your yarn around until it is fully saturated in the bleach

If you notice the yarn starts to fizz in the bleach than we can be sure it's made of a protein fiber.

For the best results you should leave your yarn in the bleach for several hours, up to 24 hours.

If the yarn is 100% wool, it should completely dissolve.

If it's a wool blend you may see some fibers remaining in the dish after the wool has dissolved away.

Other types of protein fibers besides wool will also dissolve, so this won't definitely tell if it's wool or not, but you can use this in conjunction with your other tests to be more certain with your guess.

Break Test

Another simple test you can perform on your yarn is called the break test.

For this test all you need to do is take a piece of yarn and try to pull it apart with your hands.

If the yarn breaks easily, then it could be wool.

If it's tough to break, then it's more likely something like cotton or acrylic.

Wool is known to be easy to break, which is why this test works.

However, this also can depend on the thickness of yarn.

Felt Test

The last method that you can use to test you yarn is called the felt test.

With this method we're going to try and felt the yarn together to see how the yarn sticks together.

If its wool the yarn will felt. If it's made of acrylic or another synthetic the yarn will pull apart easily.

To do the felt test:

  1. Cut to small pieces of yarn from your unlabeled yarn that you want to test
  2. Unravel the ends of the two pieces of yarn by untwisting the yarn
  3. Hold the two ends of the unraveled yarn together and push them into each other
  4. Use a little water and make the ends of the yarn damp
  5. Rub and roll the yarn together until it dries

Again, wool will stick together whereas a synthetic won't. 

So, if the felted yarn sticks together it's probably wool.


It can be difficult trying to figure out what your unlabeled yarn is made of, but running a few of the tests that we have covered in this guide can definitely give you a clue.

If you want to take out the guess work and be certain your yarn is wool, shop from our selection of wool yarn. 


Featured products

Ombré Blast Yarnyarn label info
BambooMN Ombré Blast Yarn
Sale priceFrom $13.45
Moonlight Medley YarnMoonlight Medley Yarn
BambooMN Moonlight Medley Yarn
Sale priceFrom $13.95