I thought poly thread was the one that caused so much fluff/lint and cotton didn't. So I changed to 100% cotton and get a ton of lint in the bobbing cage and around the needle. Get a little less with the poly...what's up with that? Years ago the Singer repair man told me on my Singer 2010 to use only cotton covered poly....this was his third trip to my home for repairs due to to much lint with cheap (4/$1!) thread. I started using that and never had to call him again...I was making clothes and dolls etc, not quilts. Now with my new Singer Quantum (hate it as all I ever do is thread, rethread and thread again!) and I don't see a diff in the sewing, but the lint...cotton has slightly more than the poly. Any lint comments?