I usually just rinse in as hot water as I can stand, squeeze out the excess water, and if I'm doing a bunch, throw them into the washer just for a spin cycle, then into a hot dryer. They don't seem to fray too much. which reminds me, I have a pile of FQ's and HY's that need prepping. I also hate to stop 'the creative process' just to shrink a couple of pieces of fabric.
Thanks for the hint about the colour catchers Housedragon. Will keep it in mind.