Identifying Mystery Fibers Using A Burn Test

One of the things you quickly realize about being a fiber person is that you tend to accumulate yarn. I’m not really sure how it happens (my tubes of Array are reproducing overnight), but I doubt I’m alone in having a few mystery cones on my shelves.

If you have unidentified cones that were gifted, thrifted, or purchased years ago, a simple burn test can help you identify the fiber. Burning fiber can be intimidating, but it doesn’t have to be. In fact, it can be a safe and effective tool to identify what’s in your stash. (It’s also kind of fun once you get used to it.) 

In order to do a burn test effectively,  gather the supplies you’ll need and set yourself up in a well-ventilated area that isn’t breezy. I prefer doing this with the windows open next to my kitchen sink for an added sense of security. Also, if you have long hair, I recommend pulling it back. As with any time you’re playing with fire, there is inherent risk. Be sure you set up a safe environment. 

Supplies you’ll need: 

• Your mystery yarn
• Tweezers
• Scissors
• A lighter or lit candle
• A white plate

Before you get started, familiarize yourself with the properties you’ll be looking for while your yarn is burning. 

There are three main characteristics to pay attention to during the burn test. 

1. How quickly does the fiber ignite and burn? 
2. What does it smell like while it’s burning? 
3. What is left after it’s been extinguished?

The Process

1. Make a small bundle of the yarn you're testing.
2. Using your tweezers to handle the yarn, bring it to your flame and ignite.
3. Observe how the fiber reacts to being ignited.
4. Look at how the fiber is burning and what type of smoke is rising, if any.
5. Remember to smell while it’s burning.
6. If the fire doesn't extinguish on its own, extinguish it on the plate.
7. Look at what type of ash is on the plate.

With the burning complete, take your observations and identify the fiber.

How Fibers Perform (Generally):

Animal-based fibers: These fibers tend to burn slowly and curl away from the flame. They often self-extinguish and create black beads that you can easily crush into black ash. Their odor is quite strong, reminiscent of burned hair and animals.

Plant-based fibers: These fibers burn more quickly and brightly. After they finish, they leave behind a lighter, gray ash. The smell is not as strong as animal fibers, similar to burnt paper. 

Synthetic fibers: These fibers burn bright and fast, with black smoke. They give off a chemical smell and produce hard beads instead of ash that don’t crush but feel like a melted bead. 

How Specific Fibers Behave

Wool (such as Array)

Flame: Burns slowly, curls away from the flame, self-extinguishes

Odor: Very strong odor, similar to burnt hair, smells of animal

Ash: Ends in a bead easily crushed to black powder

 

Alpaca (such as Ode)

Flame: Burns slowly, self-extinguishes

Odor: Smells similar to burnt hair, not as strong as wool

Ash: Ends in a bead easily crushed to black powder

 

Silk (such as Treenway)

Flame: Scorches, burns with a slow low flame, and self-extinguishes quickly

Odor: Smells of burnt hair, but quite mild

Ash: Ends in a bead easily crushed to black powder

 

Raw Silk (such as Sero)

Flame: Ignites quickly and burns brightly before self-extinguishing

Odor: Smells of burnt hair and animal, but not as strong as wool

Ash: Ends in a bead easily crushed to black powder

 

Cotton (such as Beam)

Flame: Lights quickly and burns brightly, smokes, and then smolders

Odor: Smells of burnt paper and a bit acrid

Ash: Leaves fine dark grey ash

 

Linen

Flame: Lights easily, burns more slowly

Odor: Mild burnt paper smell

Ash: Leaves very fine light grey ash

 

Cotton/Linen Blend (such as Duet)

Flame: Lights easily, burns slowly

Odor: Mild burnt paper smell

Ash: Clear mix of dark and light grey ash

 

Rayon

Flame: Lights quickly and burns very bright and fast

Odor: Smells of paper, but not as strongly as cotton 

Ash: Black ash

 

Polyester

Flame: Burns very fast and bright and melts with black smoke

Odor: Smells of chemicals 

Ash: Hard, dark beads

 

Doing a burn test has the added benefit of helping you get to know the fiber more intimately. The better you know the properties of different fibers, the more knowledge you have when planning projects. This will give you even more confidence when designing your own textiles. 

In fact, I think this is a valuable exercise to practice with yarn you already know. By practicing with yarn you’re familiar with, you’ll learn how the fiber smells and behaves and have more knowledge for that mystery cone. 

Here's a downloadable chart you can keep in your studio in case you ever need to do your own burn test.

About Kristin Crane

Kristin Crane began her career designing jacquard fabrics for the home furnishings industry with mills in the United States and China. Today she writes about pattern and textile design for Design Pool from her home studio in Providence, Rhode Island. Kristin weaves on a Macomber loom, a Mirrix tapestry loom, and sometimes on the go with a tiny Hello Loom. She loves to travel and is fascinated with what cloth tells us about a place and the people who live there. When she’s not in her studio, she can be found exploring the beautiful Rhode Island coastline and is rarely seen without a scarf.

 

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