I waited til there was a batch of whites that needed bleach-put the empty spools in a couple old pillow cases in the bottom of washer loaded the rest on top and let the machine do the rest. They were clean and nothing was damaged. I put them in the dish drainer to dry. Some of them were attached to a nice boards for the grand kids to hang their night cloths, on the back of their bedroom door and towels in the bath and kitchen.