All my sculptures are cast in USA
Bronze being pour inside the mold after being melted for hours at approx. 2,200 degrees
Bronze, like most metals wants to oxidize with time. The same way steel rusts, bronze wants to darken or turn green depending on its environment. With regular maintenance you can extend the life of the patina for many years.
The maintenance of bronze should consist of cleaning and re-waxing. Location and climate conditions will determine how often maintenance will be required. In general, outdoor pieces should be maintained once a year and indoor pieces as require which should be extremely minimal. Areas with harsh climate conditions will require a more frequent maintenance program for outdoors sculptures.
The first step in caring for your sculpture is keeping the piece clean. You can do this with a dust rag, soft shoe brush, or duster. If heavy cleaning is required, use a mild soap such as Dawn with water and a soft cloth. Wipe clean and dry with a rag then allow the sculpture to air completely dry before moving on. DO NOT use any type of cleanser or solvent to clean your sculpture.
Choosing a wax:
In general you want to use a clear wax. "Mohawk Blue Label Paste Wax" seems to work the best for all patinas. It goes on easily and buffs out really clean. Another choice which is easier to find at most hardware stores is "Treewax". Treewax often leaves a white residue in the lows of the sculpture. This can easily be buffed out with a shoe brush. For black, brown, and gold patinas you can use "Johnsons Traffic Wax". It goes on easily and buffs out nicely. Johnson's paste wax is not recommended for multi-colored patinas. It will often darken bright and delicate patinas.
Using a 2" to 3" round pastry brush (or a paintbrush), stipple a thin even layer of paste wax on the bronze. Lightly wipe off excess wax with a soft cloth. Let the wax dry to a matte color then buff out with a clean cloth to bring out the luster of the bronze. If desired, you can add a second coat of wax for gloss and added protection. This will also help even out the coat of wax if necessary. There is no danger in waxing the sculpture too often.
Whether you want your sculpture to age naturally or wish to preserve the artist's original patina you should keep the piece clean and free of dirt. Avoid water from sprinklers. In areas that collect water after rain, wipe dry or drill a few weep holes to prevent water damage.
Bronze has been the metal of choice by artists for centuries for its casting and color capabilities. Originating in Asia and The Mediterranean thousands of years ago, the bronze casting process varies little from the process used in ancient times. Bronze is made up of 95% copper with silicon, manganese and tin making up the remaining 5%. It will never rust and endures the passage of time well. I highly suggest you visit a foundry to see the multiple stages of the casting process because it is a process difficult to visualize unless you have seen it in person. I assure you, you will walk away with a much greater appreciation of the value and distinction of art work cast in bronze.