We source most of our deadstock fabric through jobbers who buy up "lots" of deadstock fabric at a time. The rolls will often still carry original tags from their initial runs, but sometimes we're left in the dark. Burn tests are how we determine fabric content for the beautiful pieces we couldn't pass up, in order to be as transparent + clear about what you're purchasing. Doing burn tests also helps me decide what to order, and how to price fabric as fairly and as accurately as possible. So settle in as I take you through the ins-and-outs of burning tiny scraps of fabric for fun!
PSA: Please do this outside. I foolishly attempted my first go in the kitchen – burning polyester is not a fun smell to get out of your clothes, trust me.
What You'll Need:
-A tin pie plate or bowl wrapped in tin foil
-A lighter or matches
-A scrap of fabric about 2 x 2" long
-Long metal tweezers
The first step is to take a good look at a burn chart like the one below – it's helpful to memorize the basic categories as things get going pretty quick when you're holding a scrap of burning fabric!
Credit: National Safety Apparel
The next part is pretty straightforward: take a scrap of fabric & light that shit on fire (safely! outdoors! with tweezers! in your tin bowl! with water nearby!). You're going to want to smell the smoke, observe how it burns and check out the ash (or lack thereof) that it leaves behind.
I did a burn test on a few pieces from the starting lineup, to show you a bit of the process:
Linen/Cotton Blend: Our supplier guessed that this was some mixture of linen/cotton, but I did a burn test anyways to a) determine exact percentages and b) ensure there were no synthetic fibres so I could price it accurately. As you can see, the fairly equal percentages of grey and black ash show a fairly equal composition of linen to cotton, with no synthetics blended in.
Charcoal Performance Knit – Yup, this one's a synthetic (a big duh from the crowd.) I knew this was a recycled poly/lycra blend from an attached tag, but wanted to do a quick burn on it to show you the difference between a true synthetic and natural fibres. See how the edge is curled over and melted, with lighter coloured blobs? That indicates a high polyester count – but as the smoke smelled like celery, I can tell that there's probably some nylon in there as well. And the ash that you see in between the harder bits of polyester? That's the spandex.
Silk is one of my favourite fabrics to burn – geez, how decadent does that sound? The scent is immediately distinguishable (and honestly a bit repulsive) – it smells exactly like burning hair. The fabric curls away from the flame, leaving behind a black bead that, unlike polyester, crumbles to ash when touched.
I fell in love with the gorgeous drape & colour of this fabric at my supplier's warehouse, but wasn't exactly sure of the composition. I'd guessed it was a cotton blend, perhaps viscose or polyester. The burn test revealed that cotton was definitely present ( see the stringy fibres between the black beads?) and that it was mixed with polyester rather than viscose or a more natural fibre (rayon/viscose would crumble rather than leave a hard melted bead behind.)
This is an interesting example of a primarily cotton twill with a bit of something acrylic on the external fibres. It's hard to see in this picture, but some of the fibres melted a little at the edges, while most of the fibres burned and left a grey & light black ash, indicative of cotton. I'd peg this as a cotton twill that's woven through with a polyester coating to maintain the weave & add sheen.
My supplier had guessed that this was a rayon/linen blend, but again wanted to be sure so to the fire it went! As rayon is made from cellulose, it's technically a 'natural' fibre – at least, it tends to burn as such. This fabric is not self-extinguishing – an easy, immediate way to tell if something is completely natural. (Most acrylics extinguish themselves after a short period of time). It's hard to tell exactly what percentage of rayon is present, but my guess is that it leans more heavily towards linen, as there isn't much grey ash present. Also interestingly is that the black ash might indicate mercirized linen, a treatment often done to wool, cotton and linen fibres to add lustre.
And here they are! Hope this helps you in your quest for fabric perfection – some die-hards even bring a portable kit with them when they go fabric shopping. (Of course, ask for a swatch and take it outside!)
(A caveat that burn tests can't be 100% accurate – certain fibres are woven through one another that it's impossible to distinguish exact percentages. But it does give a great guess as to what a fabric's composition is, and is quite easy to tell if there is an acrylic present, or if it's a completely natural fibre. )