I just realized that I have some older (unused) white all-cotton muslin sheets (the package says 134 threads psi - and that they are "sanfordized" to reduce shrinkage to 1%) I've been dreaming of an old fashioned "cottage-y" type quilt in light blue floral & white - could this be used for the white?

Sheets are used as backing so I say why not ? Maybe prewash ?

Lots of people use sheets for backing. I used a sheet on my first quilt! I didn't know enough to use 100% cotton, but it has help up fine over 30 years!

Many use cotton sheets, so I don't know why not :D:D:D

I'm glad I remembered I had them - thanks! :-D

You sure can I have used them for backings and for piecing
on the front I buy the flat sheets for backing and the fitted for piecing, works for me :D

Yes I used a sheet as backing on my quilt for my mom. It worked perfectly so I don't see why you couldn't use for the front cotton is cotton. I would recommend washing them though.

I use them all the time, and mostly use sheets for backing fabric. Higher thread count sheets are more difficult to hand quilt through, and cotton sateen can be slick to work with, but I never have any problems using sheets. I think it is against the quilt police guidelines, but I frequently use vintage sheets, and I buy flat solid sheets at places like Ross and TJMaxx and use them for backing all the time. Have even made a couple of whole cloth quilts with interesting sheets.

Not long ago someone on an email group I'm on posted about some quilts she got, I believe, from her aunt (after she died maybe). Anyway she was dismayed that these quilts had sheets for backing because, as she said, "real" quilters never use sheets. Quite a few people, including me, did not agree. I have not used sheets in a quilt but that doesn't mean I never will.

Thinking about it, I bet that way-back-when, old sheets were probably used quite often - along with old shirts and dresses. The more I think about it the more I think it would be perfect. Now I just need to start a new bin for yet another project to come....