I have been told in the past that thread that is not 100% cotton is stronger, & when weight/stress is put upon the quilt, the stronger polyester thread will cut through the cotton fabric. If using 100% cotton, the stitch will just pop if weight is placed on the seam. It is much easier to catch a stitch or two than to try to mend a seam line that has been sheared trough by tough thread!

See superiorthreads.com on the subject of poly thread not cutting through fabric

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would not use chemicals such as petroleum products, glues, fabric softners, or anything else that could be an allergen in my quilts.....the dyes in the fabric are enough chemicals for me......unless it is a wall hanging I would not use metal, plastic, glass, crystal,etc. Just my preference, which is why we quilt.

Don't they say that Poly filled pillows are allergen free? They're the down alternative. I can't be near feathers or I start to puff up, all of my poly pillows are hypoallergenic... Some natural products are allergens too.

My machine seems to prefer cotton. I have problems with poly and poly blend threads more often than I do with cotton.

gale, what tension adjustments do you do to the machine when you change from cotton to poly? All of my machines here will let me run anything I want.

I've tried all kinds of adjustments. Tension (tried both ways), different needles, newly wound bobbins, etc. It just doesn't seem to like it and I prefer cotton anyway, so I don't worry about it anymore.