The Coloring and Patinization of Bronze

 Coloring Treatments for CAST Lighting Fixtures

When it comes to durability and appearance over time, bronze is the clear winner. This is why the best designers an specifiers select these metals in their landscape lighting projects. While the untreated surfaceof bronze ages beautifully to a patina or verdi, there are occasions when either a different color fixture is needed or when the patina color is desired immediately upon installation.

There are numerous formulas and treatments used to achieve these color changes. Manyof them involve the use of dangerous chemicals and extremely time consuming procedures. For this reason, we spent a full year talking to the experts and experimenting with their suggested techniques.

The recommendations detailed below involve relatively simple formulas with ingredients that are readily available. We are confident that the two treatments will yeild the desired result of color changes that are easily accomplished, long lasting, and suited for the outdoor environment.

Precautions:

Note: To ensure that the homeowner will be satisfied with the final appearance, treat one fixture first and show it to the homeowner.

It is important to note that anytime you are working with chemicals (no matter how safe) that you should take precautions

  • Wear rubber gloves
  • Use eye protection
  • Work in a well ventilated area
  • Do not allow children in the work area
  • Store chemicals in a clean dry area out of reach of children
  • Thoroughly clean all containers and work areas before and after use
  • If you are spraying installed fixtured, cover surrounding plant material with plastic

Patina - Greenish-Blue
While "patina" refers to any age-induced color changes, it is the word commonly used to describe the greenish-blue copper sulfate oxide created when bronze and copper naturally age.

These metals will naturally paina over time, but the following treatment is instantaneous. This is frequently desired by the homeowner.

Formula:

  • 8 oz Ammonia
  • 8 oz White Vinegar
  • 1/8 cup Salt (use of rock or kosher salt may result in different colors - experiment)
  • 1 teaspoon Spreader/Sticker
  • 3 Drops Dawn dishwashing liquid

Procedure:

  1. Out-of-the-box fixures require no pre-cleaning. If the fixtures have been outdoors for some time, you should remove dirt and bird droppings with a cloth, steel wool or a wire brush.
  2. Fixtures that have already been installed and undergone color changes can be treated. If the surface of the fixture has gone to old-penny borwn, further treatment may result in a darker color (compared to treating the fixture out-of-the-box). If the fixture is in the chalky-white stage, then this whitish coating should be removed with CLR prior to treating.
  3. Add the ingredients to a small hand or pump sprayer, in the order as listed above. Make sure the ingredients are completely dissolved and mixed well.
  4. Use a fine mist to apply the mixture to the light fixture. Do not soak the fixture as this will create runs and pooling of the mixture ande lay drying. The reaction (patina) will happen very quickly and allow you o see where you may have missed and apply additional coats for even coverage.
  5. All the fixture to dry before handling or apply the mixture with the fixture already in its place. If spraying around plants, make sure to protect thm from the spray since both formulas can burn like a highly concentrated fertilizer.

Brown Coloring Process

Formula:

  • 8 oz Water
  • 1 teaspoon Liver of Sulfur (if needed, crush with mortar and pestle to a uniform powder)
  • 1 teaspoon Spreader/Sticker

Procedure:

Use the same procedure as with the Patina.

Note: This formula turns bronze a nice dark brown, but does not work well with copper (very streaky). For this reason, do not use on fixtures with copper stems or shrouds.

Warranty: Coloring fixtures will not affect CAST's warranty, but the fixtures can not be returned because you don't like the coloring.