A flat twin sheet. From IKEA.
I have been looking for the perfect sashing and I think this is it. This flat sheet (100% cotton) cost about $5.00. I did some math and it is equivalent to 4.25 yards of fabric. That's a GREAT deal and I don't need a coupon when I decide to stock up. I love that it's lighter weight than Kona Cotton or Quilter's Only Cotton (from JoAnn's), but heavier weight than bleached muslin. It's a nice creamy white, which blends well with both white and cream toned fabrics. It's so easy to use and frays very little. I have used sheets to back quilts occasionally, but until now, that was about it. After a test drive using it for sashing, I think I'm hooked!
You can see in the photo the scrap project I worked on to test the fabric. I'm (a little) obsessed with these little stars, which finish at 6" square. Eeek!
I'm curious, what's your favorite sashing?