I made a wall hanging a couple of years back for DD's anniversary and did not pre-wash......to my horror the dark green fabric let go of ALOT of it's color! I then had streaks of green on my cream background and gold stars. I felt just SICK! :!: I had to work very hard at trying to get some of those streaks out and they didn't all come out. So...I will never take a chance of that happening again and I pre wash anything darker than white. :D :D :D In order to eliminate the agitation and all the tangled up mess in a washer, if you are worried about some of the colors, I would think you could rinse your darker colors in the sink and lay them on a towel to dry.