Most of the time I pre-wash (because "they" say I should :wink: ), but I really like to work with "new" fabric. With all the steaming I do before the final top is finished, I think the shrinkage has already happened. I haven't had problems (yet) with bleeding. When I pre-wash, I just smooth the pieces out fresh from the dryer. I press befoe cutting (most of the time :oops: ).