I have used upholstery weighted fabric in quilts. I am not usually a prewasher, but this in an exception. When I use any non quilter's cotton fabric I always prewash in the same conditions the quilt will be washed and dried. I also cut and hem a certain size like a 6.5 x 6.5 square and remeasure afterwards for shrinkage. I mostly use them as backs, or lightly pieced (not a lot of seams) backing for applique or log cabin (not a lot of crossing seams)