I've started using these sheets in all my laundry. I just told Mom about them, as she lives alone and has hi water bills and I thought she could combine some of her laundry loads. Sometimes they come out just as they went in, so i lay them aside and use them again. I prewashed some reds and the new sheet was just as red as the several reused sheets. The other weird thing I found out this week...my DH's work clothes.... black T's and jeans that have been washed for a couple of years now.....the sheets I threw in still came out a dark gray! Didn't expect that at all and sometimes I've been known to throw in some other dark colors in with those black clothes......hmmm, now wonder they don't look so bright anymore.
The second thing: I went to Amazon, thinking I could get them cheaper, but since I needed a box right now, I found that WalM had a cheaper price than ordering them by the carton from Amazon....somewhere about 3.50 for a box of 24.
And I don't know how they used to keep dyes from running, but I suspect that they prewashed everything, as I was taught to do when I first started sewing in the '60's. And before that, I think everything probably was prewashed simply because they recycled their fabrics from draperies to clothing to quilts to who knows what.
I like to wash the quilt when it's finished. On the one I made for MOM, It instantly showed me a spot that I had pulled out FMQ and hadn't redone. So that was a good thing. You can always iron and starch them out flat again if you don't dry them all the way in the dryer. I know, Cause that's how I fixed Mom's! and o yeah, I have a black dog.......

