I probably shouldn't admit the following.... I do my own long arming and I never prewash or square up the backs. By not washing, I am insured that the shrinkage will happen after it is quilted and I like the "vintage" crinkly look. Once in a while I get a surprise bleeder, but plenty of color catchers helps with that. I do cut off all the selvedges. I have seen them shrink a lot more than the rest of the fabric and I don't want the quilt drawn up at that joining seam.