How to Determine if a Thread is Bonded Nylon or Bonded Poly?

[Evo160K]

Is there a way of determining which is which?  A search of the LW forums didn't provide an answer.  Thank you.

[mikesc]

Polyester feels "softer" and they react differently to flame / heat.

[shoepatcher]

Both threads will melt with heat.  poly normally has a slightly softer feel in your fingers.  Poly should not have a lot of stretch to it.  Nylon will have more stretch.   Al, nothing on the spool as to  numbers or letters?

glenn

[Evo160K]

Thanks Mikesc, thanks Glenn, that gives me a good frame of reference.

Glenn, the question was more general than specific.  Thanks

[Uwe]

I found this on another forum at ybw.com. Haven't tried it yet myself, but may be a good way to put your nose to use as a highly sensitive chemical analysis tool.

"Take a few sample strands from each rope. 
One at a time apply a flame to a sample, for sufficient time to cause it to just burn unaided and immediately extinguish the flame by blowing or dry smothering. The fumes that emit can be useful in identifying what the plastic is.

Nylon has a smell not unlike burnt hair.

Polyester has an offensive acrid odour, nothing like burnt hair.

Read more at http://www.ybw.com/forums/showthread.php?124455-Nylon-or-polyester-How-to-tell-the-difference&s=9c080cfdd0cd0c3f78fa965f0d72a61f#Emc4PbrLqSiCspql.99

[Evo160K]

Well that's interesting, I'll try it..  Thanks Uwe.

Having been in the safety business for many years, I've tested clothing fibers looking for synthetics by holding a flame near to see if they melt, but I've never smelled them.  Synthetics will melt around flames and molten metals and stick to the skin....cotton burns to ashes.

[Colt W Knight]

I have nylon on my top thread and polyester on my bobbin, and when I melt the ends after sewing, the nylon melts and the polyester will melt and catch on fire.

 

[Evo160K]

Thanks Colt, very much appreciate your input.