I weathered my coveralls with watered down acrylic paint what’s the best way to set the paint in so it won’t be washed out?
You honestly don’t even really need to water down your acrylic paint to weather your coveralls. If anything that will just make it more likely to wash out. If you watered it down to lighten colors next time just mix your darker paints with lighter such as grays/whites/light browns etc also even some of the metallic grays/blacks work amazing as well. If you are meaning washed out as in actually washing them in a washing machine that isn’t a good idea after weathering with paint. You more or less don’t want to wash your coveralls once your weathering is complete. They shouldn’t get too stinky if your only wearing them in costume/cosplay. Also letting the paint sit and your coveralls getting them self naturallly weathered does them a lot of good as well. There is something called fabric medium that you mix with acrylic paint the help bond it more to the fabric. I myself am not a fan of it at all, i believe the acrylic paint itself without any dilution bonds just fine by itself. Also dabbing your brush in a little olive oil as well as the paint helps it to absorb in the fabric better as well as making the weathering much more realistic.