I messed up once trying to use a "thermal" weave blanket. Decided real quick that was a mistake. But I use sheets, blankets, comforters, even mattress pads if they are good quality material. The real plastic stuff is OUT!

We use blankets all the time at the charity I participate in. We can get them free or cheap at the resale stores. Make sure they are clean and tie them up. We do not "quilt" our quilts, we tie all of them because cost would be out of site with all the quilts we do. Have used many different innards. Polyester material, washed of course, flanned sheets, make nice batting and not too heavy. Yes, we too are into the recycyle mode there.

best thing I ever used for batting was a mattress pad...it was sew perfect and it looked great. I did use a blanket for a quilt and it was nice and thick.

I have used flat flannel sheets many times. Just make sure you shrink it first. I like using the sheets when I don't need a "puffy" look. However, it can make your quilt too heavy, so check that.

A blanket is OK. If you want a warm top, don't quilt it too heavily.

Blankets have often been used as battting. But be careful, don't use anything that is scratchy, I have my husbands grandmothers quilt here, it wore from the inside out and was just in shreds. I think the bllanket wore out the cotton on the quilt. I ended up cutting it up last xmas and made stocking for his family.

I have used a blanket for batting.. Do not do it often but in a pinch it is fine to do....
I have heard that an old quilt can be used for batting as well....never tried that though.

I agree, using a blanket that has been washed works fine. I have also used plain white cotton hospital blanket for backing.

By all means, use blankets. I had 3 brothers in WWII and my mother used their blankets as batting for years. Also, there may may be a military surplus store near you where you can sometimes get blankets for $5. Check them out. Should you find some wool blankets, be sure to preshrink them several times. They will be warm and cozy and heavier than regular batting. Should one not be large enough, get some of the tape that seals batting edges together and press the edges together until you can get it quilted. Hope this helps.

I've used blankets before with no bad results. Don't know what you'd call them, but not the loose weave thermal type.