I would use it on ANYTHING - All I use is Poly and I LOVE it!

depending on the weight of your thread will depend a lot on what you use it for. If it's 40 weight, its embroidery, 50 wt is quilting as is 30 wt. If you use it for embroidery just match your bobbin and you should be good to go. have fun and feel very lucky. Would love to get 45 spools of thread, any weight, any color, any brand!

Have you tried it for FSL? I think it would look very 'old fashioned' for that. I haven't tried it, but I intend to.

just remember to clean your bobbin area after each use, as cotton builds up a lot of lint. also check around the needle area, i've had it build up there as well. use mine for quilting, sewing, putting fancy stitches around outside of bibs, blankets, etc. also have used it for fsl, but select designs with lower stitch count, as cotton is thicker thank polyester. good luck. betty

Alice - it is wonderful for cutwork, especially if the material is a linen. Lucky girl.

Cross stitch. Makes it look more "hand done" without a sheen to it.
Jo

I use cotton thread quite a bit for towel designs, fsl and lace. It washes better and seems to last longer than the polyester. It doesn't have the sheen as polyester or rayon. Sews up well. experiment and have fun with it.

I'd make a sample design of one of the dark colors and wash in hot water and dry to see if the color doesn't run. If it runs you can use on items that are not generally washed often.

If it is 40 or 50 weight use it for free standing lace.
EastWitch2

I use poly a lot just like rayon but stands up to washing much better and bleaching. Does not fade like rayon. You can do anything you want with it just like Rayon. Suzanne

Everyone had great answers but have you thought of donating it to a group that makes charity items? I'm sure someone would be willing to take it off your hands and put it to good use.

I like the idea of using it for FSL. I use cotton alot for that. If all else fails, I'd be happy to send you my address! Hehheheheheh! Carol

Lots of ideas here but one thing for sure.....don't get rid of them. You'll use them at some point. Ya gotta love thread!