I’m getting ready to back a 50" x 70" lap quilt and checked the bolt of 100% cotton white muslin that I bought a while ago. It seemed stiff, so I thought I would prewash it, but the label says “line dry”. So, I’m assuming if I put it in the dryer, it will shrink (a lot?). What would you do? Would you cut 3 yds. - wash it and put it in the dryer; wash it and line dry it; or just iron it and hope for the best? Is 3 yds. enough to cut for this size quilt?