I wanted to know if I use the invisible nylon thread would it melt if put in a hot dryer or if I had to run an iron over it?

I'm not sure about the nylon melting, but the Poly invisible is much nicer in a quilt. Very soft! I didn't have any problem with melting when I used it.

I use the poly invisiable and have never had any problems. I use it for applique if I don't want to take away from the design. Don't use it for baby quilts. If your stitches are very big, little fingers can get caught.

I have used poly and washed, dried and even ironed it and all way well.

Nylon will stretch when used in machine sewing and that will cause lot of tension and breakage problems. It's not very strong either. That's why it's cheaper than the poly invisible thread.

Some of the older nylon thread will melt... maybe not very noticeably the first time, but each time the iron hits it is weakens.

Doesn't nylon cut the fabric as well?

I use Sew Art nylon and I tried to fry it with the iron and I couldn't so I went ahead and used it extensively. It's so strong that I do worry that it could eat away at the cotton fabric over time, especially in the laundry but I've heard a claim from someone that's been using it for years that it hasn't happened.

When I made my first quilt top (in the last century) and which I am still hand quilting, I used nylon thread (serger thread, actually) and it did not melt when I pressed the blocks/quilt. It is, however, one of the many, many wrong things I did in making that quilt. That WIP gives a whole new meaning to the term, "Practice Quilt".

i just finished a quilt using poly, YSL. it doesn't melt, but i hated it. i couldn't see what i was doing. i wouldn't machine sew with it again.