The Oil Rubbed Bronze finish is achieved by immersing the metal in a special heated solution that oxidizes the metal to a desired degree, after which a mixture of oil and wax is applied and rubbed in. When dried, the excess oil is removed. The appearance will changed based on environmental conditions and the wear from usage. The areas of the lock that come into contact with your hand will “polish up” and expose the base bronze metal, while untouched areas will continue to oxidize and darken with age. This can be controlled to some extent by the application of a non-abrasive auto wax.
Recommended care for the Oil Rubbed Bronze finish is as follows: Wipe with a little vegetable oil on a soft cloth (a very little, or a residue will remain which will transfer to your hands). Household detergents and mild abrasive powder may be used to restore the high metal color without affecting the original compound of the metal. Use fine steel wool soaked in #10 oil then coat with furniture paste wax.
Oil rubbed bronze (613) is considered a category “B” finish by ANSI/BHMA and will vary in color when applied to different alloys and forms of base material. 613 will also vary from production lot and additionally from one manufacturer to another. Oil rubbed bronze will wear off over time due to the “rubbed” finishing method that has no protective coating or plating.