I do the hot water/Dawn in measuring cup test.....really works......BUT, I only test anything primarily red or navy blue...those are the ones that seem to bleed if they're going to bleed....and actually I seem to stay away from those.....I do not pre wash anything else for quilts, but if I am doing a tablerunner or placemats I will pre-rinse fabric with hot water so the finished product does not pucker in the future (use poly thin batt).