Leviticus 13:57-59

But if the mildew comes back to that piece of leather or cloth (either woven or knitted), the mildew is spreading. And whatever has the mildew must be burned with fire. When the cloth (either woven or knitted) or the leather is washed and the mildew is gone, it must be washed again; then it will be clean. “These are the teachings about mildew on pieces of cloth (either woven or knitted) or leather, to decide if they are clean or unclean.”