Assuming the quilt blocks are cotton... Use only the gentlest detergent, like Woolite in lukewarm or cool water in a basin. Divide all into color piles. Wash only the white/lightest at first, by just squishing the suds through, using your hands, patting them instead of wringing, and letting them soak. Rinse, and dry flat and evaluate your results: Press gently, and examine the seams. Then do some slightly darker blocks, only blues; only greens; only pinks, etc. How much color is coming off into the water? Do the darkest ones last. If you are satisfied that your blocks are washable and the seams are worthy, then go ahead and make a quilt. Best of luck to you.