This isn't a clear thread, it looks like a fiber thread.
Nylon thread stands up to heat. It yellows at 300°F and melts at 500°F.
Nylon thread has excellent resistance to mildew, aging, and abrasion.
Lots more info here:
http://www.thethreadexchange.com/miv...y_Code=BNLSPEC
I got 12,800 yard cone for $8.!! So it was worth trying it out good or bad. I love trying different threads.