Thursday, January 10, 2013

Resource Library: Burn Tests


IDENTIFYING FIBER CONTENT - BURN TEST

No special equipment is needed to do a burn test. Use caution and have water available when doing the test. Do the test on a non-flammable surface like the sink or a metal covered table away from any flammable objects (curtains, paper, etc.) Do not do the test near an air conditioner, fan, or open windows; keep your hair and face away from the flame. Use tweezers.

But before starting your burn test remember natural fibers, those harvested from plants or animals leave a breakable remain, either ash or a bead that turns to powder when crushed.

Man-made fibers are formed by combining monomer compounds into polymer molecules. Many of the polymers that constitute man-made fibers are the same as or similar to compounds that make up plastics, rubbers, etc. For this reason a majority of them will leave a hard bead when burned.

Animal Fibers - Proteins:
All kind of wool (including alpaca, angora, camelhair, cashmere, mohair, etc)

Plant Fibers - Cellulose:
Cotton, Linen, Flax, Ramie, Mabu (100% wood fiber), Bamboo, etc.

Most common man-made fibers in textile industry are:
Polyester, Acetate, Nylon, Acrylic, Rayon, Modal
Rayon and Modal are polymers of regenerated cellulose, which burn similar to natural fibers because of its cellulose content. Rayon is manufactured regenerated cellulose fiber, Modal is cellulose fiber, made of 100% beech wood cellulose.

To review: Natural Fibers will leave ash or a crushable bead, while most of the man-made fibers will leave a hard melted non-crushable bead.


THE TESTING PROCESS:
To conduct a test, cut a small swatch of fabric. Holding it with the tweezers use a match or  a lighter with a small flame. Light the swatch with the flame and observe. Be very attentive since the fabric might catch the flame fast and you will have a short amount of time to observe the following:

1. How fast it burns?
2. What is the smell like?
3. How does the residue look?
4. How does it burn?
5. How does the flame look?


NATURAL FIBERS - CELLULOSE:
Cotton:  Depending on where the cotton was harvested and the process used to manufacture the fabric, its thickness and weave will burn fast or slow, but always steady once it catches the flame. When burning, observe the core of the flame. The residue is black and shows almost all of the ash that is going to leave after you get to blow the flame. Once the flame is gone, an orange amber might keep on burning, leaving ash. It smells like burning paper or leaves. The residue will be gray or black powdery ash.

Linen: Linen burns similar to cotton, but burns at a steady speed leaving gray ash. 


ANIMAL FIBERS - PROTEINS:
Wools: Burns slowly and will extinguish if flame is removed. It smells like burning hair or feathers. Leaves a brittle black ash. Crushes into grainy powder when touching the residue.

Silk: Burns slowly and will self-extinguish if flame is removed. Smells like burning hair. Leaves a breakable grayish bead that turns into soft grainy powder when crushing it.


MAN-MADE FIBERS - POLYMERS:
Polyester: Produces an orange flame with black smoke. When burned it has a sweet smell and melts leaving a hard black bead. Sometimes polyester is blended with other polymers that will leave a whitish bead. In case of this, observe the flame. If it produces black smoke and the bead is hard, polyester is present.

Nylon: Burns and melts with a sizzly noise. The flame has a blue core. Leaves a hard grayish or brownish bead, smells like burning celery and will self-extinguish after flame source is removed. There is no smoke present in burning nylon.

Acrylic: Burns and melts with an acid smell. Leaves a hard black crust. Will continue to burn after flame source is removed. There is no smoke when burning acrylic.

Acetate: Burns and melts with a sizzly noise. Has an acidic or vinegary smell, and will leave a hard black bead. Will continue to burn after flame source is removed.

Rayon: Burns moderately and rapidly. As it burns you will see the residue curl. When blowing away the flame, an orange amber keeps on burning almost all of the ash. There is almost no ash left when the amber is finished burning.

Spandex: Melts and burns, smells like burning rubber, leaves a black ash. Finding spandex content is best figured out by stretching the fabric with the weave. Do not stretch it on bias, because all fabrics stretch on bias. 


MY NOTES:
Burn testing at home helps you find out the main fiber content of an unknown fabric. Blend fabrics are difficult to test at home but not impossible. Sometimes looking at the "sheen" can help identify the fabric content. 

- Silk can have a shiny nature to it. This is especially helpful if you have a silk/cotton or silk/wool blend. After you burn it and it gives you possible silk and cotton characteristics, it can be confirmed by looking at the sheen.

- Rayon also has a natural sheen, but not as shiny as silk. Rayon/ linen and rayon/ wool are common blends. When burning a rayon/ linen, it may burn more like linen but you may still be unsure. If it has a sheen to it, it could have some rayon it is as well. (Rayon also allows the linen to wrinkle less. So ball up a piece of linen and a piece of rayon/linen. You will see the difference in the crinkle. 

- Wool and acrylic have non-shiny, curly fibers. 

- Cotton fibers are longer than linen fibers, therefore creating a more slubbed look. 

Blended fabrics will result in mixed residue and mixed smells. Spandex is used in small percentages to produce stretch in fabrics. Burning spandex does not dramatically change the characteristics listed above when present in the fiber content.



Be careful when doing your test. Never panic if the fabric catches fire quickly. Just let it fall on the non-flammable surface and observe. Have water ready, extinguish the fire and try again.

Good luck in your testing and if you have questions, do not hesitate to contact us.

~ Gabby ~

2 comments:

  1. I am an eighthee and I was asked which synthetic fibre burns with the smell of burning hair. This blog does not seem to show any such results.

    ReplyDelete
    Replies
    1. Fibers that smell like burning hair are going to be natural fibers not synthetic, unless there is a natural fiber mixed with the synthetic as a blend.

      Delete

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