Blocks are hard, are you going to make a quilt out of them? Washing the quilt is easier. I have used this recipe on vintage cotton clothing and laces: equal parts Ivory dish soap and clorox 2. Tepid water and just set the block in don't agitate just kind of squish, rinse the same way, I usually rinse at least three times. If there is a really persistant spot try to solution on a q-tip rubbing gently. Rust spots are hard to get out. Blood try a solution of Hydrogen peroxide and water on a q-tip. good luck, marie