I never pre-wash fabrics because I son't like the way they feel and handle after they have been washed. I only buy premium fabrics (always on sale) and I usually only buy Moda and I've never had any problems with finished quilts shrinking above the 2 to 3% that the manufacturer warns about. Premium fabrics are colorfast and if I have any doubt I'll cut a small piece and soak it in warm water to see if it bleeds. I always wash in cold water on gentle cycle and dry on the lowest settling of my dryer. Most manufacturers don't recommend pre-washing pre-cuts.