What’s That Fiber? The Identifying Trick Every Fiber Lover Should Know

As a crafter, there are few things I find more frustrating than falling in love with a mystery skein of yarn. I acquire a beautiful unlabeled hank of goodness just begging to be used, only to be stopped short by not knowing what the heck it’s made of (and therefore how to use it). With all the yarn that travels in and out of the Interweave offices, I’ve become familiar with the woes of mystery skeins.

So what exactly do I do with these unknown fiber sources? Set them on fire, of course! No, I don’t mean setting the whole mystery skein ablaze, but rather using the fiber-burn test. This is an identification technique every fiber lover should know, as it can help you identify what your mystery skein might me made of. To show you how to identify your own mystery yarn using the fiber-burn test, I rounded up a couple of colleagues to play a little in-office game called “What’s That fiber?”

fiber burn test

Before starting, there are three main steps of the fiber burn test you should familiarize yourself with.

Before starting our own fiber burn test, we went over the three types of fibers: cellulose, protein, and synthetic. Keeping in mind that no fibers will ever burn exactly the same way, here are the general characteristics of how each fiber will burn.



After familiarizing ourselves with the steps and the characteristics of each fiber during and after burning, it was time to let it burn (cue the Justin Timberlake music). To better illustrate how each fiber acts, I selected yarns that I had labels for, but I kept their contents a secret to the end. It was up to my poor coworkers to use the fiber-burn test to figure out the fiber content for themselves.

Jenn went first . . .

Jenn selected a glossy soft gray yarn. After igniting it, it burned quickly and left a distinct plasticy smell in the air. After waiting for it to cool, she noticed the hard balled-up burnt end that was left behind.

What was her guess?

Next was Hannah . . .

Hannah’s yarn was green and slightly hairy. It was hard to tell if this yarn burned fast or slow;after burning, the smell was strong but hard to pinpoint. Her guess was:

And then Andrea went . . .

Andrea selected a super-soft pink yarn. This yarn burned more quickly than others and left a distinct smell that was reminiscent of burnt hair. The ash left behind crumbled easily. From these clues, she guessed:

Sara followed after . . .

Sara’s soft gray yarn also ignited and burned very quickly. She noted a smell in the air that reminded her of burned paper.

Her guess was:

Last was Kerry . . .

Kerry tested a white yarn with multiple twists. Her fast-burning yarn left light-colored smoke hanging in the air and a glowing ember after being extinguished.

Kerry guessed:

So how did they do? Jenn was correct and did indeed burn a synthetic yarn: Caron Simply Soft. The sleek spin and smoothness of the yarn was the first tip-off to its synthetic content. And while this yarn, like most other synthetics, burned quickly and receded away from the flame, the real giveaways were the plastic odor and hard ball it left behind.

Perhaps we didn’t wait long enough for the smell of Jenn’s yarn to clear the air, because the smell from Hannah’s yarn had her choosing synthetic instead of protein for her 100% superwash wool from Cloudborn. Protein-based yarns can be some of the hardest fibers to identify via burn test since they range so greatly in type. If you find yourself with a mystery yarn even after the burn test, try burning a couple of known protein-based yarns and compare the results.

Andrea was the unfortunate recipient of one of the hardest yarns in the bunch to identify: Manos Del Uruguay’s Serena, a protein/cellulose blend. Since the blend was more alpaca than cotton, Andrea picked up on the smell of protein fibers first and identified it as X.

Sara also got one of my tricky yarn blends to identify, and she came really close to identifying the cellulose/synthetic Conway from Valley Yarns. This yarn was more cotton than acrylic, so Sara was able to pick up on the papery smell.

Kerry was right on the money by guessing cellulose for the 100% cotton Mika from Classic Elite Yarns. The glowing ember left behind was a dead giveaway of a cellulose-based fiber, and as someone noted, it smelled ”just like a campfire.”

Our little game of “What’s That Fiber” was a great example of the benefits of conducting a fiber-burn test for a mystery skein. While it’s not a 100% accurate way to determine fiber content, it can lead you in the right direction and help you turn that mystery yarn into a finished object.

Happy fiber burning!

Ready to turn that mystery skein into an FO?


One Comment

  1. Lori B at 11:05 am July 1, 2018

    My problem is differentiating between linen and cotton fabrics. If it’s spun the right way cotton can do an excellent impression of linen. Any suggestions?

Post a Comment