How to Do the Burn Test

By Claire Ortega-Reyes – 12 Comments

There are many ways to identify what kind of fiber or fibers is in yarn. Obviously, the label tells us the exact composition of the yarn (100% acrylic, 50% cotton 50% acrylic, etc.). But what do we do if the label is gone forever?

We can turn to texture. If the yarn is coarse, it should be acrylic; if it’s a little hairy, it should be wool; if it’s shiny and slippery it must be silk or rayon. Then again, modern technology has made acrylic yarn soft and shiny; there are even acrylic yarns that look like mohair yarn.

Enter: the Burn Test. When yarn is (quite literally) tested in fire, its fiber composition is seen more clearly.

Here’s what you’ll need:

  • a long strand of the yarn(s) to be tested
  • tweezers or tongs (to hold the yarn with)
  • match or lighter
  • candle
  • a bowl of water

We’ll need a safe place to conduct this experiment. The ideal venue is a working sink, so if the flame goes out of hand, a water supply is readily available. It also wouldn’t hurt to have a fire extinguisher near you (just in case!). If there are any kids or toddlers running about the place, make sure they’re napping or busy before doing the burn test.

So let’s get started! Light the candle with your matches or lighter. With the tweezers or tongs, grasp your yarn and put it near the flame. From here we rely on our senses to distinguish one type of fiber from another.

Synthetic Yarns (Acrylic, Nylon)

  • Smells like burnt plastic
  • Flame does not extinguish for a long time, continuing along until blown on or submerged in water. Warning: don’t pinch the burned end; the melted synthetic material might cling to the skin.
  • Yarn seems to be “eaten up” or melted by flame
  • Does not leave ashes
  • Burned ends turn black and harden

Plant-Based Yarns (Cotton, Linen, Rayon)

  • Smells like burnt linen
  • Flame continues to burn until blown on or submerged in water, much like candle niches
  • Flame is easy to extinguish
  • Fine ash, much like ashes from burnt paper, is left behind

Animal-Based Yarns (Wool, Silk, Alpaca, Angora)

  • Smells like burnt hair
  • Flame almost immediately dies down on its own
  • Leaves charred, crisp ashes

It’s easy to tell the results of the burn test when the yarn composition is 100% of the same fiber. Today, though, yarn mixes are popular, combining the strengths of different fibers to produce a yarn intended for a specific project. What to do in this case?

The burn test should manifest the majority of the fiber content of the yarn. But if you want more specific results, and the yarn is stranded, you can untwist your yarn to reveal the different strands or plies of yarn, and test each individual strand.

I hope that was helpful! If you need anything, just leave a comment below.

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  1. Heather says:

    I think I might be able to make this into a chemistry lab. Thanks for sharing this!

  2. Des says:

    Nice article. I have lots of yarn purchase from garage sales and there are lots of skeins with missing label. I have been trying to figure out how to guess the fabric content of those yarns.

    Thanks for sharing

  3. Steph says:

    Thanks for this. The hassle of not knowing what it’s made of means I often don’t buy yarn I see at thrift stores.

  4. Diane says:

    And if a moth eats it, it was wool…..

  5. Doris says:

    This is so neat. Thanks for this info. I didn’t think about lighting my yarn on fire to figure out what it was made of. I’m going to try this (but of course when the kids aren’t around).

  6. Heidi says:

    You must be careful doing this!!! There were several yarns about 5 years ago or so that burned like gasoline. Bernat Disco being one of them. they were recalled but if you are a true yarnie you probably still have a skein in the stash….

  7. gig says:

    Thanks for this. I tested a yarn that I was sure was wool, and it is very clearly acrylic. I only use wool for certain things, so that frees this yarn up for other uses.

  8. deborah says:

    thanks so much for this useful info.

  9. Jean says:

    don’t know hwere to post this don’t see a ‘contact me button so here it goes…
    I was using your pattern of Basic Preemie hat and am having trouble
    being sure whether you wanted us to slip stitch join between rows
    and then chain 2 before beginning wach row.

    are you having us do this “in the round’ with no slip stitch

    I’m having trouble following the directions as you say without needing to ‘on my own’
    use a slip stitch to join the circle and then chain 2 to begin the next row of hdc.
    please help me conqour this do you have a video??

    thanks Jean

    • Rachel says:

      Hi Jean, the preemie hat is done in the round like a spiral. But you can do the chain at the beginning and the slip stitch at the end if you like.

  10. Jean says:

    This a Thank you Rachel for getting back to me regarding the instructions on the Preemie hat. I will try to do it as a ’round like a spiral’ as you say because I am getting ‘gaps’ when I try to do it with slip stitch and then chain 2 to begin next row. I think it will make it even smaller in size which is what I need it to be. I am currently making these preemie items to give away at a local hospital where they say that they greatly appreciateand need these items! Be blessed Rachel for all you do! Will be using more of your patterns and am making baby preemie blankets as well.

  11. Cynthia says:

    I really appreciate this article on the burn test. Just wanted to give you a flow chart I found on the internet of a more complete identification of the different fibers offered. I was a Fashion Design Major many years back at a 4 year university. I had an entire year of the Science of fibers and what not. We were given stacks of fibers to identify for our exams, some of which were very mixed when woven or spun. I wish I knew where my text book was…I didn’t get rid of it, it just packed some place from the several moves I have done over the years. I had forgotten about some of this but will always remember trying to distinguish all the smells. We had to crush the ash with our fingers to feel the texture of the ash as well as smell to get exact identifications. You definitely want to wait for the ash to cool to crush it. Some of you may enjoy a more detailed description list, especially since there are so many more fibers out there, than when I was in school. I am sorry to say that Bamboo is not on this chart, even though it has become an important fiber in yarns and fabric. And very important, this is not to be done around or in front of children. You do not want to suggest to them that lighting a match to a yarn or fabric can be fun or interesting. You never know how cute creative minds will interpret seeing an authority figure light a match to a piece of yarn or fabric and what it could lead to. Do it in a well ventilated room as some of the fibers can be toxic and smells quite strong. I remember all to well the smells in the classroom after the exams! And I have been to some well meaning Boy Scout Flag Burning Ceremonies (for proper disposal of torn and tattered flags). Some of the flags are made of nylon or polyester as well as cotton. Pee-U!

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