What is a coating I can put on a steel washer to make it safe to wear against skin or clothing? For context: I was out at the site of my great grandfather's sawmill and took a washer from the old boiler mount. I want to get it engraved and coated, but don't want it to rust if I wear it under a shirt, or for the coating to rub off onto clothing. Is anodising the best coating method, or is there another method better suited for this purpose? #industry source