BRONZE SCULPTURE RESTORATION
Bronze is one of the earliest metals known to man. It is defined as an alloy of copper. Our foundry uses modern bronze that consists of 95% copper, 4% manganese, and 1% zinc. However, it may also include small amounts of aluminum and nickel. Because bronze contains a large amount of copper, it oxidizes over time when exposed to air, but only on its outer layer. This oxidation consists of copper oxide. The copper oxide layer protects the interior metal from further corrosion. However, in the presence of chlorides, copper chlorides form which can form “bronze disease”, a condition which corrosion works through the metal destroying it.
Chlorides are highly prevalent in ocean air, and are a major component of sea salt aerosol. These chlorides are produced by breaking waves and spray. The salt air chlorides are not limited to the coast, and studies have found significant amounts of sea-spray chlorides hundreds of miles inland, an example being in Boulder, Colorado.
As mentioned above, copper oxide is actually a protective covering of bronze, but this oxide layer can develop into the destructive copper chloride. The copper oxide destroys the patina (color) of bronze sculptures and covers the sculptures with a white, unsightly, and rough surface. But again, and very importantly, in the presence of chlorides in the air, the resultant calcium chloride can destroy the metal surface of the bronze. When copper chlorides are exposed to moisture, they undergo a rapid chemical reaction that produces hydrochloric acid. The acid eats into the healthy bronze and causes the metal to pit, crack, and erupt from the inside out.
Frostad Atelier Foundry, under the hands-on direction of Ronnie Frostad, is a leading foundry in the United States for the restoration of bronze sculpture. Ronnie has personally restored many nearly destroyed sculptures back to their original beauty. We have numerous clients throughout the U.S. who utilize our foundry restorative services for their personal fine art sculpture collections. We are the foundry for the City of Sacramento and have restored many valuable pieces for the highly-respected Crocker Art Museum in Sacramento. Ronnie has restored and maintained many large outdoor sculptures in the Hawaiian Islands including the world-famous Fernando Botero collection which is installed at the Grand Wailea (Waldorf Astoria) resort in Maui. However, small sculptures can be restored in the foundry with the client either shipping or hand delivering their sculptures.
The bronze restoration process involves heating the bronze surface with a propane torch to loosen the bronze oxide layer. The oxidation layer is then removed by hand. Any rough surfaces due to the oxidation process are smoothed which sometimes requires light welding with silicon bronze welding rod. The patinization process then follows which is the artistic application of chemicals with heat to produce the client’s desired colors. Wax is then applied to the finished surface which helps to maintain stability of the restored sculpture for many months.
The patina process requires a great deal of skill to be able to apply the correct chemicals for the desired color. Ronnie is an excellent patineur with many years of experience. Being an artist herself, her work is very unique in that she restores the fine details back in the sculpture that include such things as shadowing and blending/feathering of colors to prevent sharp edges. On large surfaces, the patina is sprayed on the surface, but on small detailed areas, Ronnie actually applies the chemical to the surface with a fine brush and then heats the chemical with a propane torch.
Many restoration projects, like the Botero sculptures at Maui’s Grand Wailea, are located in various parts of the United States. In these cases, Ronnie usually travels alone and performs the entire restoration project by herself, but with projects closer to our foundry, her staff assists her. However, wherever the sculptures are restored by Frostad Atelier Foundry, the final results are always exquisite.
BRONZE SCULPTURE MAINTENANCE
Once an outdoor bronze sculpture is restored and waxed, it should be maintained on a regular basis. With regular maintenance, often on 6-month intervals, the treatment usually requires the application of minimal chemicals and wax. Frostad Atelier Foundry offers regular maintenance for our clients. The desired revolving schedule can be arranged by calling the foundry business office.
BRONZE SCULPTURE REPAIR
Frostad Atelier Foundry receives many requests each year from around the U.S. for repair of prized bronze sculptures. A client’s sculpture may have been damaged in shipment often with separated parts, cracks, or dents. Unfortunately, we see too many sculptures that have been vandalized, and many involve monumental-sized sculptures that cannot be moved and must be repaired on site. However, the majority of our repairs are on smaller pieces that can be hand-delivered or shipped to the foundry. Most damaged sculptures can be repaired to the point where the damaged section is not visible.
Many clients are surprised that their sculpture that they purchased for a reduced price is made of brass or other alloys but not bronze. Many brass sculptures are cast in developing countries like Nigeria and India. Brass is softer and less durable over time than bronze. As a result, brass sculptures are more easily damaged than bronze, but they can usually be repaired in our foundry.
Bronze (brass) sculpture repair involves TIG welding the damaged section with silicon bronze weld for cracks and assembly followed by finish of the bronze welds for blending. Patina is then applied.
BELOW ARE EXAMPLES OF BRONZE SCULPTURE RESTORATIONS BY RONNIE
