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Fabric Friday: Determining the fiber of a fabric

Discussion in 'PUBLIC Workshops - specialty vintage topics' started by denisebrain, Jul 23, 2021.

  1. denisebrain

    denisebrain VFG President Staff Member

    This is just slightly adapted from the Determining Fiber page of our Fabric Resource.



    If you have a piece of vintage clothing without a fabric content label and you’d like to know what the material is made of, try the most accessible test out there: A fiber-burn test. The basic process involves snipping a small piece of fabric from an inseam, then carefully burning it with a lighter while observing how the fiber behaves (looks, smells, feels) during and after. You can then compare your findings to a chart.


    There are a number of tests, some traditional but potentially inconclusive (such as dampening and creasing a fabric to see how it behaves) and some quite scientific but not accessible to the average person (exposing yarns to certain chemicals and examining them under a microscope). By far the most accessible test is burning.

    Burning fibers takes practice, and you must start with a little caution. Tie long hair back out of the way. You should burn over a sink or bucket so you can allow the potentially molten fiber to drip safely, and drop your sample if necessary. You need a pair of tweezers to hold a small fabric swatch, and a lighter. If you burn matches of any sort you will pick up the scent of burning paper or wood, throwing you off for discerning the burning fabric’s odor.

    If you are testing a finished garment, find an inconspicuous place to cut a small sample, usually a seam allowance. Even a few yarns are “readable” with experience, but a piece of about 1” × 1/4” is ideal. Hold one end of the fabric with the tweezers and slowly expose the other end to the flame of the lighter. Notice if the fabric readily burns or takes some effort to light. Also, note if the fire burns out or continues until all the fabric is burned. Smell the smoke as the fire goes out. Finally, when the sample is cool enough, feel the residue and note its color. Compare your findings to the standards in the burn chart, below.

    _big_vintagefashion-new_22410.gif


    Of course, many textiles are made of fiber blends. Pull apart warp and weft yarns and burn them separately, as the blend may be as simple as one distinct fiber in the warp, another in the weft. Another test is to untwist an individual yarn and burn the plies separately. In both these cases, try to bundle and twist together like threads so that you have a swatch of sufficient density to burn accurately. Other blends may seem inconclusive, but feature a “top note” that is discernible—such as the “burning feathers” odor of silk. Even knowing part of the fiber is helpful.

    To train yourself about how a fiber burns, try taking clippings of known fabric samples and get used to each sample’s characteristics when burned.

    You can find YouTube videos of fibers being burned, and that may help with the visual side of the process.

    Several factors may effect how a fabric burns, including finishing treatments, density of the weave, and even the dye used.

    Your senses also will help determine a fabric’s fiber content without burning, given a chance to learn. With experience, silk, wool, rayon, polyester, acetate—all fibers, are discernible just by look and feel. Spend time handling known fabrics; keep your own swatch book to compare. If you have a chance, be taught first hand: You may be fortunate to find a person who is knowledgeable about textiles and can guide you. Experience with a fabric mentor could make a complex project much easier and more memorable.



    One technical test of fiber content available to the average person is microscopic examination, using a relatively inexpensive hobbyists’ or children’s microscope (just 100x magnification is plenty for this purpose). Photos of magnified textile fibers can be seen in books and online.

    I don't own this, but I'm considering ordering this hand-held microscope: Carson MicroBrite Plus 60x-120x LED Lighted Zoom Pocket Microscope (This is an Amazon affiliate link. That means if you click on the link and purchase the item, the VFG will receive a commission at no extra cost to you.)

    On another level, a technical evaluation of solubility uses hazardous chemicals to test fibers. Generally these tests are only run in laboratories. One test of this kind, though, is available to the average person—using acetone. (Look for pure acetone among nail polish removers.) At room temperature, acetate will dissolve in acetone (brush it on with a cotton swab). Triacetate will disintegrate. Modacrylic and vinyon will soften.



    I know that a number of people struggle with the fiber burn test for various reasons. (Someone told me recently that it sets off the smoke detector in her apartment!) What can I, or one of us, do to help?
     
  2. Midge

    Midge Super Moderator Staff Member

    Brilliant, Maggie!

    I dove into burn tests after first reading about them here, but I admit it hasn't always been easy. I guess it mostly was due to mixed fibers. I should defintely try to get more into it by trying it with known fibers from my fabric stash.
     
  3. denisebrain

    denisebrain VFG President Staff Member

    That’s the way Karin! Grab known things to test to train yourself.
     
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  4. Vintagiality

    Vintagiality VFG Member

    I struggle with them because I am so focused on not burning myself and the house down and because it usually happens so quickly that before I even figure out where on the chart I am, and what to look for next, it’s gone. I also struggle because I don’t actually recognize or don’t differentiate sufficiently some of the smells described. What do burning feathers smell like? Burning grass vs burning paper? In my mind they smell sort of the same, though it depends on the grass I guess.
    Lastly, I don’t fully understand certain aspects of this chart. Say for example I have determined that it is self-extinguishing, burns and melts, and smells like vinegar. The next step in the chart is “hard black irregular ash” but what if it isn’t? There is no option for that. The chart step doesn’t “split up”. And if it always is in fact acetate or triacetate if it smells like vinegar, than what’s the point of the ash part? I don’t get any of those single option parts on the chart.
     
    denisebrain likes this.
  5. denisebrain

    denisebrain VFG President Staff Member

    I’m so glad you asked all this—thank you Victoria.


    If you fear being immolated, try setting a candle in your sink instead of using a lighter. There is a little less juggling to do, although the candle may have some of its own scent to separate out. Use something longer than a tweezer—maybe pliers. The scariest fiber being burned for me is polyester because it can drip while molten—sometimes even flaming drips. You are right to be careful!

    To me, one of the easier parts of this is deciding if the fiber burns readily or not. Wool is practically inflammable. The manufactured fibers that burn and melt look like they are shrinking from a flame. The burned cellulosic fibers are pretty distinctive in smell and the fibers quite flammable.

    Let’s talk about the odors. You know how in wine tastings people describe the taste and odors in really metaphoric, overblown ways? I mean like, “grass, charred pineapple, brambles, and cigar”? And you’re thinking it smells and tastes like wine? It’s a bit like that with fibers burning—it can be a bit of an exaggeration.

    One thing that may fool you is that the odor is not necessarily going to be discernible while the swatch is flaming, but more when it has just burned out. It can be painful to breathe in the smoke while it’s flaming, and it is harder to tell the scent.

    Feathers or hair burning are the characteristic smells of silk, wool and hair fibers like alpaca, camel, cashmere, angora, mohair, etc. Makes sense, right? They are all animal hairs. If you can spare a tiny bit of hair (maybe from your brush) you can try burning that and see what it smells like. Or anyone with a fluffy dog that you’ve just brushed or who is shedding—

    I don’t think burning grass or paper or leaves or wood are all that different in odor either. In other words, all the cellulosic fibers (linen, cotton and rayon) smell a lot like a fireplace fire when burned, and all create an ash.

    To me, burned acetate smells like vinegar with paper. And if you think it is acetate but aren’t sure, you can dab it with pure acetone and it will literally dissolve.

    Because a fiber burn test has a number of variables, we really can’t expect it to follow paths perfectly. Once you get more used to doing this test, if you get results that seem mixed, I would quickly suspect that it is a blend of fibers.

    If it’s a blend, and it is obviously something you can take apart, like a silky thread and a cottony thread that cross over one another, you can burn one and then the other. If the fibers are blended in each yarn, all you can do is see if you can smell a top note.

    Another tip is to have a suspicion to start with. Let’s say you have what you are sure is taffeta. What could it be made of? If you don’t know, try looking in our Fabric Resource where it names the characteristic fibers for the fabric, which in this case are silk, rayon and acetate. By far the most common of these is acetate taffeta, so that is a good suspicion to start with.
     
    Last edited: Jul 24, 2021
  6. mags_rags

    mags_rags VFG Member

    I have a pair of tweezers that I keep with my measuring tape so I can easily find it when I am working on descriptions. I have gas stove burners, so turn a burner on as low as it will go and then hold the snippet to the flame using the tweezers from a few inches away. But as I was writing this, I had an even better idea. I found these on Amazon searching for roach clips
    ::ironing::
    @Midge worth adding to the VFG-recommended items for Amazon affiliates?
     
  7. Distantdetails

    Distantdetails Administrator Staff Member

    This is all such good advice. Thank you.
    I'm printing these out, until I can get a chance to try everything out. Perhaps we can host our own version of "Burning Man Festival", and do this in person, enough times until we get it right.
     
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  8. Vinclothes

    Vinclothes Alumni +

    As I have noted before in another post, the admonition we got as children to not play with fire, really stuck. We are not recommending starting a bonfire. A tiny, tiny flame is enough-over a sink, a metal pan, a flower pot, an ash tray...
    Be brave, Marian
     
  9. The Vintage Merchant

    The Vintage Merchant Administrator Staff Member

    such good suggestions and descriptive explanations here, Maggie. thank you!



    and i love this. such a great, helpful suggestion.
     
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  10. Vintagiality

    Vintagiality VFG Member

    Thank you Maggie @denisebrain
    Those are all wonderful tips. I will give it another try. The thing is that the fibers most discernible via a burn test are also frequently most discernible visually and via touch. For example, I usually am better with things like silk and cotton or wool. The ones I am having a hard time with visually are also the ones that give me a hard time via a burn test.
    I also struggle with the weave because what’s more distinctive in magnified images of fabric is not how the fabric looks without the magnification. I frequently find at least three or four possible matches for the weave and they are totally different fabrics so I struggle with narrowing it down.
    I know it takes a lot of practice but I feel like I have been at it for 10 years and I have only marginally improved.
    I bought a whole bunch of fabric swatch books and keep trying to test myself but the results are mixed at best.
     
    denisebrain likes this.
  11. The Vintage Merchant

    The Vintage Merchant Administrator Staff Member

    i feel the same, not only with fabrics, but for the life of me, i have a very hard time distinguishing between different types of fur.
    it seems like it should be easy deductive reasoning "if this, and this, then this", but i find that it baffles me.
     
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  12. denisebrain

    denisebrain VFG President Staff Member

    You aren't the first person to say this, and I am going to add to the Fabric Resource photos of characteristic garments in the fabrics as I can. During this weekly session, I will show examples and maybe those can go straight into the resource.

    Here are a couple of fiber blend burn tests in action at 8:40 in this video. She mentions something important about polyester: You can see black smoke when it burns.



    If you start at the beginning of the video, you can see the results of burning cotton, then linen. Notice the subtle difference. As Claire has mentioned, if you burn a large enough swatch of linen, you will get a lacy gray ash in the shape of the swatch—linen keeps its shape much better than cotton or rayon.
     
  13. Vintage Runway

    Vintage Runway VFG Member

    Great post! Thank you so much for your time and effort. Very helpful!
     
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  14. denisebrain

    denisebrain VFG President Staff Member

    It's a pleasure to do this Suzanne—I truly love fabrics and appreciate learning more and discussing them.
     
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  15. Midge

    Midge Super Moderator Staff Member

    That video is very helpful - and a good idea to do it with a tealight. I have a lot of those around that I never use! I will add the tweezers to the shop.
     

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