Cut a small swatch of the fabric in question and put a match to it--the edge of cotton will burn, polyester will melt.

My concern with mixing the two is uneven shrinkage. Prewash and dry it all first to avoid any unpleasant surprises on the final product.

And as the fabric burns, cotton leaves behind a fine ash while polyester leaves behind a sort of melted blob of plastic feeling stuff - it's made from oil remember.

The burn test is perhaps the best way to determine fiber content. This works for silk and wool also; they will leave behind a fine ash too.

Teresa

I usually can tell when I start using it thinking it's cotton. Once you touch it with an iron, you get a funny smell. With experience, it happens less and less as I can now pretty much feel the difference.

I accidentally bought a small piece of navy blue poly cotton solid - the bolt must have gotten mixed in with the other solids I was buying, and sure enough, as soon as the iron hit it, I could tell it was a poly cotton mix even though I had prewashed it. I looked at my receipt to verify it was poly cotton. The iron feels 'slicker' on the poly & has that funny smell, esp when you have the iron on a hot cotton setting.

I think that they can be mixed if care is taken. When I started quilting that was about all that was available and my first quilt had a poly/cotten which hasn't caused any problems. That was 30+ years ago. For that matter it was the backing as I remember. Now I don't do that but as a beginner and not having many choices it worked. Jayne

I inherited boxes (plural) of material from my mother and also when people find out I quilt, I've been the lucky recipient of more when people clean out their caches. My mother's is old enough to be mostly cotton, because pre-sixties that was the norm. Perma press? Didn't exist and the first entry into that was drip dry. Does anyone remember that? LOL.

I have several catagories of quilts I make now and my scrappies (at least every other quilt is one) I mix fabrics with abandon. You will not turn into a pillar of salt, or have seven years of bad luck if you mix them. To me, the poly blends have a softer 'touch' and may not give you the look you want if used in large blocks if you want crisp. Cottons can. However, I buy into the philosophy of the quilter as a recycler and no piece of fabric leaves my house......it is always used for something, even if it's ripped up and used for rugs.

If I am giving an heirloom gift, like for the birth of my g'son.........it's all cotton and all new. However, I use my quilts daily (the few I have kept) and they see the inside of my washer on a regular basis. I call them utility quilts and I have not seen the dreaded after effects so often forcast with mixing the fabric media. They are just as durable as all cotton.

I believe there is a higher percentage of OCD-ish-ness among quilters than the general population. I would have a seizure if I tried to use a poly blend in a quilt, but then I've always hated polyester in clothes, too. I'm too sweaty.

Thank you all for your responses.

calliope, I was kinda worried about that pillar of salt thing. lol

The scrap quilts I'm making are utility quilts. I feel a lot better about using what I have been given.

petalpatsy I think i will still twitch a bit when using the poly blend but when I make an heirloom quilt I make sure it is all cotton.

Thank you all, again, for your input. I'm going to continue on with wild abandon and see how things come out in the wash (literally).