I like using poly for piecing, no lint at all. About it damaging cotton fabtric, I have read that most 'people that know this stuff' say they have no idea why that caution was ever so popular. Bottom Line by Superior is 100% poly and Sew Fine is poly. Anyway, use a good brand of thread for piecing and look at what other class members are using. You will find the thread you like and your machine likes by experiementing. Right now I'm using Essential thread by Connecting Threads for my piecing. I like it and my machine likes it.