when i buy yardage and first wash in hottest water, i use the lowest level and wash each piece separately. i know i'm using a lot of water, but it's the only way to know which one is the one that might be bleeding. i also use use detergent. what the hey, get it all out in the open before i begin.
after all, which do you want first, the good news or the bad news?
when i buy smaller bits, i BOIL (that's the hottest water) and then let dry. i figure the boiling will do whatever can be done to it.
if i really love something that bleeds, i try again with retayne. sometimes that works. i would use that for a wallhanging. i don't trust it for bedding that will be washed regularly. i never count on things like salt or other home remedies. however i have had reds that never gave up. in those cases, i did.