Put a lit match to a corner of the fabric. Cotton will char burn but blends will melt.

I usually cut a piece off so I don't have major damage. Keep a cup of water around or a bit of water in the sink so put the fire out. If it has a bead it should stay on even if it is wet - if not do it again carefully. I so hate getting burned.

Go to Google, type in "how to test cotton fabric". Tons of information will pop up.

I just went to goodwill and sal army bought a bunch of the infant shorts dresses that have the snaps at the top I'm going to sew across the bottom and then take them to work for my residents to use on the side of their wheelchair and there walkers. with the snaps on the top of the outfit easy on easy off, really got some cute ones and when i sew them you'll still be able to see the design on them, also stocking up on kids jeans for a jean quilt

Have done that for special reasons, made a fun family quilt with pockets of shirts and jeans and decorations from shorts etc. Also a plaid using son's shirts, and throws using daughter's clothes, fun to do.

I repurpose 100% cotton curtains into quilts especially when looking for fabric with a faded look.

We have a open market sale here in the summer where we can only sell repurposed products. A GREEN market as it was explained to me. Did not partake of this summer but might next summer. Lot of scrubs that have not sold(used) and they are destined to become quilts. Used sheets for backing, used blankets for batting. Except for baby ones of course, those get new batting and backing on them.

I rather recyclr than buy new, I can live rich of what people throw away,

I DO shop thrift stores, goodwill etc. I have found some family member's discontinued dish pattern on more than one occasion. I have not yet found a sewing or craft "find", however I do re-purpose at home. If a garment is unfit for donation and must be tossed, I remove the buttons, zipper and if it has nice ribbed cuffs in good shape them too. Jeans beyond repair? Cut the legs off and make denim squares from the parts that are still in good shape. Shirt buttons are fairly generic. I remove the whole set and put them on a large safety pin or paper clip so the matching buttons stay together.

I went to a bed bath beyond store on their finally day a few years ago, Everything that was left was 25 cents I had so much fun got a lot of quality material to repurpose I am still using it. I made a quilt that was all new material the top cost 1.00