lock finishing Yes, you can use Jax Black on the exterior lock parts. Topics: Products_KitsTags: Finishing|Metal Darkening|LockLast verified: 2026-08-31Also called: finishing, finish, stock finish, final finish, metal darkening, darkening, jax black, browning, bluing, rust blue, charcoal bluing, patina, lock, lockplate, lock plate, lockplate assembly, lock assembly