I'm a prewasher, because my eyes water whenever I'm in a fabric shop. I must be allergic to whatever chemicals are in the fabric. I'm glad I am, because at least 5 times out of 10, my color catcher comes out with color on it. Yesterday, I washed the fabric I bought from Thousands of Bolts - all blues which are notorious for running. The beautiful dark blue backing ran buckets, so I treated it with Synthrapol. The other blues were ok - surprising, because 2 were dark blues. I didn't measure the shrinkage, but I could tell there was some, because all the cuts were 1 yard pieces, and some were shorter than others after ironing! Doesn't matter, because I bought more than I need for the current project. I need more blues in my stash!