The solar radioactive radiation will burn off all body oils and slowly beak down salts on fabrics. You must have direct sun to do this after the wash. Continuously spay with water every time they dry until sun-bleached. If it is colored turn it inside out and upside down. The ring around the collar disappears if you add charcoal starter type fluid to your white wash with the soap. Great grandma added kerosene of course to help the home made soaps.