mine are navy so they don't show dirt much. this weekend is making me a prewasher!! good thing it was a test block. a light fabric i had cut (luckily oversize) shrank before my eyes. I had just wacked some pieces to starch heavy since it would be bias and as soon as I touched that one with the iron it shrank 3/4 of an inch. I went ahead and used it since I was working on technique but doggone. 3/4 of an inch.