Wednesday, January 11, 2017

Sorting Cottons from Man Made Fibers: The Fire Test Day 10

Unknown Fiber Contents:
Fabric Samples Above and Below

I've gotten some fabric donations, and like all the rest it went through a wash and dry cycle. It helps me to know fiber content before using the fabric, and paying attention to it during this process gives me clues.

Shake out a piece of polyester or nylon blend fabric from your washer, and it smooths fairly quickly. Cotton tends to stay bunched together, and usually has more wrinkles.

Pulling it out of the dryer is an even bigger clue because man made fibers tend to have fewer wrinkles. Notice I said tend because that's not always the whole story. Some cottons are treated with chemicals that make them wrinkle far less now. It's just hard to tell so sometimes I do a burn test to know for sure.

 This scrap was cut from a piece that only measured 30" selvage to selvage. That size yardage is generally attributed to the 1930's and 1940's--before polyester came around, but this fabric was so smooth I suspected that perhaps it wasn't pure cotton.

This came from the dryer with almost no creases at all, and I highly suspected it contained quite a bit of polyester. That's not unusual for these kind of prints. I laid it on a stone counter on top of a piece of foil, and lit it with a grill lighter.

From the start, it took a few seconds to actually light.

Immediately it began to curl, and there was a lot of black smoke. A residue starting forming on the right.

It took several rounds of relighting to fully burn it, which is why polyester is recommended for children's sleepwear. The part I don't understand is that it forms hard, shiny beads that stick to the foil. (I know it sounds horrid, but wouldn't this stick to your skin?)

The vintage sample was easier to light, but also had to be restarted a few times. This sample turned out quite different, though.

The only thing left when the embers were out was a bit of ash. It completed disintegrated. This is all cotton.

There are further ways to evaluate fabrics into nylons, etc. according to burn tests, but for my purposes I know enough. The poly blends go in one pile, the cottons in another. It's not that I don't or won't mix them, but there are times I do need to know. For instance, any kind of accessory for your kitchen like a pot holder that might come into contact with high heat would melt like the samples above. It's all good to know.

I wish you all well this month, and keep on sewing for charity!

Come on, Doxie girls.

Let's go sew, too.


Emma Robertson said...

Really interesting stuff, thanks for sharing. ��

Lisa J. said...

I wish you well this month and I promise to keep on sewing for charity.

Kate said...

Yes, that would stick to your skin. Which is why if you work in areas that require flame resistant clothing (FRC), it's highly recommended that you wear only natural fibers underneath your FRC. Synthetic fibers would melt in high heat conditions and cause burns just as if you external clothing caught fire. How do I know? My spouse often works in areas where FRC is required due to the presence of high concentrations of flammable materials.