Iceblossom, your melt experiment is interesting. I’m going to try that with some older thread I have. Yesterday I saw this on the Superior Threads site:
”Polyester fibers recover quickly after extension (the term elongation describes the stretch and recovery) and absorb very little moisture. Polyester is heat resistant (dryer and iron safe), with a melting temperature of about 480º F (in comparison, nylon starts to yellow at 350º F and melts at about 415º F). Polyester fibers are colorfast, resistant to chemicals, and can be washed or dry-cleaned with most common cleaning solvents.”
I've been using 80wt. Deco Bob, a Wonderfil product. I couldn’t find a melting temperature listed, I zoomed over to Panosonic and discovered my rechargeable iron only heats to 350^. But when in doubt, you experiment is the obvious solution.
This 80wt thread is the bomb! I can’t even feel it in the seam at all, and my blocks are flat. There’s just one problem, I’m having trouble seeing it.