We love to sleep on high thread count sheets, but the higher the thread count the least likely you should use it as a backing. The combination of a high thread count and the needle size used by longarm machines.. make it likely the stitch hole will break the fibers and it will be a true hole. I once ha a long arm pro take out a good amount of stitches on a batik backed quilt. When I noticed the " holes" where she had made a mistake and taken out a very large section of quilting.. she told me not to worry they will close up. Well they never did, batiks are also a higher thread count, I can still see every hole the needle made. I almost wish she had left the original stitches.