Prism99

I would hand wash the two bow tie blocks in a ***lot*** of hot water and Synthrapol to see how the colors fare. Chances are good they won't bleed. However, if the dark color does bleed, the bountiful amount of water will dilute the bleed and the Synthrapol (requires hot water to work) will keep the loose dye particles suspended in the water so they do not settle in the other fabrics. A bath tub would be a good place to conduct this experiment, or a top-loading washing machine.

Assuming the dark fabric is not a "runner" (never stops bleeding) and any dye bleeds are relatively small, you would be safe to wash the quilt at the laundromat using their largest front-loading machine, ***hot*** water, and Synthrapol. Just be sure to remove the quilt immediately after the machine stops so that the damp wet fabric is not staying in close contact with the white fabric. Toss in dryer (what I would do) or dry flat on carpeting or outside on grass ***in the shade*** with a flat sheet underneath and another flat sheet on top (to protect against bird droppings and also to further protect against light, which can fade fabrics fast).

Things you do NOT want to do. (1) Wash in a domestic front-loading washer. These machines do not use enough water to dilute dye bleeds. (2) Allow the quilt to be agitated in a traditional top-loading machine that has a central post. The central agitator puts too much stress on the quilt. (3) Allow the damp quilt to remain balled up. You need to flatten it out so damp dark fabric is not rubbing against damp white fabric.

There is no way to "set" colors at this point. It can only be done chemically on individual fabrics. Trying to use any kind of setting chemical on a finished quilt only ensures that any dye bleeds are likely to become permanently set where they do not belong. You want to use something like Synthrapol that will allow any loose dye particles to be removed from the fabric.

Personally, I would not dry clean a quilt like this, especially since you have a couple of blocks you can experiment on first. My expectation is that the blocks will still be totally useable even after treating as I describe above, as any dye bleeds should not settle into the wrong fabrics. I would definitely wash the blocks by hand to prevent raw edges from ravelling. (Thick rubber gloves are helpful, as is a wood broomstick for swishing the blocks around in the water.)

Edit: I like the Q-tip suggestion. However, if there is color on the Q-tip I would definitely go further and do the test wash on the extra blocks.