My favorite sweater and backpack accidentally got tagged with white paint today. Are they permanently ruined, or is there a way to remove the paint? I'm thinking about simply trying paint thinner, but I'm not sure it will work... And just in case someone happens to know, the paint was being used on cinder block walls. So what type of paint would that be (oil, water, acrylic, etc)? Sweater is 50% cotton, 50% polyester. Backpack composition is unknown.