I can remember the sheets from my grandmother's day....they were white, quite thick, and we pressed them after hanging on the line to dry, of course they were 100 percent cotton. The sheets now seem to be thinner and can often be a blend...for my church charity quilting group, we use a lot of sheets for the backing and often for sashing and borders but then again we also use a lot of different fabrics, whatever can be stitched as most of the fabric is donated...I personally do not use sheets in my quilts because they just don't have the same feel as quilting cotton. But...whatever you decide is fine I think. I would not use them on any quilt that was difficult and time consuming to piece even for the backing as the effort and time on put in on the top deserves a good backing. For a quilt that I was expecting to be used and abused and tossed when tattered, I just might.....but I have a huge stash and am working on using up a good portion of it....