FLYMPH FORUM

If a thread spool has no name on it, how can you tell if it is cotton or silk. My wife picked up a ton of spools from an estate but no labels are available.

Some are spun on sewing bobbins and some are not.

Any suggestions would be appreciated.

I think you have to burn a little bit and smell??


Greeting

What a great idea Ruard. i would not have thought of that. Makes sense to me.

Silk, when burnt leaves an ash like cigar, synthetic melts and smells like nylon or plastic burning.
This is also a good way to confirm old fly lines as silk or some kind of nasty braided nylon.
However, I do not know if the "burn test" will distinguish beyond doubt between cotton and silk sewing threads..... must go do a test.

As several folk have pointed out, both silk and cotton will burn, not melt. Cotton tends to burn to an ember, while silk does not -- but the real test is that burning silk smells like burning hair.

Burn criteria for fibre identification.
Natural Fibres

Cotton: Burns, but does not melt. It has the odor of burning paper,
leaves, or wood. The residue is a fine, feathery, gray ash.
Hemp: Same as cotton
Linen: Same as cotton
Ramie : Same as cotton
Rayon : Same as cotton
Silk: Burns, but does not melt. It shrinks from the flame. It has the odor of charred meat. The residue is a black, hollow irregular bead that can be easily ground to a gritty black powder. It is self-extinguishing, i.e., it burns itself out.
Wool, and other Protein Fibres: Burns, but does not melt. It shrinks from the flame. It has a strong odor of burning hair. The residue is a black, hollow irregular bead that can be easily crushed into a gritty black powder. It is self-extinguishing, i.e., it burns itself out.

Manufactured Fibres
Most manufactured fibres both burn and melt, and also tend to shrink away from the flame. Other identifying characteristics include:

Acetate: Has an odor similar to burning paper and vinegar. It´s residue is a hard, dark, solid bead.
Acrylic: Has a fishy odor. The residue is a hard irregularly-shaped bead. It also gives off a black smoke when burned
Nylon: Has an odor likened to celery. It´s residue is initially a hard, cream-colored bead that becomes darker.
Olefin/Polyolefin: Has a chemical type odor. The residue id a hard, tan-colored bead. The flames creates black smoke.
Polyester: Has a somewhat sweet chemical odor. The residue is initially a hard cream-colored bead that becomes darker. Flames gives off black smoke.
Spandex: It burns and melts, but does not shrink from the flame. It has a chemical type odor. Its residue is a soft black ash

There are various other descriptions of burn tests and the various smells. To make sure you can recognise the smell, burn something you know first. Don't inhale a lot of smoke! Just sniff it.

Use a butane gas lighter with a clean flame.

Thank you cassady! I am going to go try it out on some old threads that I have.

This group never ceases to amaze. Thanks for all the useful info. What a cool thread.

William Anderson wrote: What a cool thread.

Thought it was "hot"

If you have a microscope you can do it "cool";

http://msnucleus.org/membership/html/k- ... m6_8d.html

http://www.alpinemeadowsguild.org/fiber_microscopy.html

https://fril.osu.edu/

http://www.onlineclothingstudy.com/2012 ... d-man.html

Thank you all for the advice, I will try it to see what I got!