How to Clean Anything Made of Bronze
You likely have a lot of things in and around your house that are made from bronze, like sculptures (both inside and out!), address markers, awards, bells, lamps, jewelry, and even musical instruments. Keeping these items clean can be tricky, since bronze has very specific requirements when it comes to care and maintenance. We spoke with Ted Roberts, the owner of Art Recovery Technologies of Greater Kentucky, a Prism Specialties brand, to discover exactly what you should know before you begin cleansing the metal.
Bronze is a metal alloy that primarily contains copper and tin, says Roberts. "Foundries who cast bronze often have their own 'recipe' and add other ingredients such as arsenic, manganese, phosphorus, etcetera," he says. "These recipes are developed to yield different properties in the final product." When exposed to air, bronze oxidizes, which causes a patina on its outermost layer. "The dark or greenish brown patina that forms on bronze is highly desirable and should be preserved," he explains. "Never use metal polish or solvents on any bronze. For indoor bronzes, dusting alone should suffice."
According to Roberts, when it comes to cleaning bronze, the simplest method is always best. "Our recommendation for cleaning bronze sculptures is plain soap and water," he says, adding that they prefer a dishes-specific variety. "Be sure to avoid any soaps with additives or scents that might create unintended consequences." After you've given your bronze a thorough wash, rinse it and dry it very well before applying a coat of wax. "Try to do this when the metal is still a little warm. This allows for the wax to enter the pores and act as a barrier to the air and humidity that can cause the bronze to over-oxidize and turn green, which may not be your desired result."
Using cleaners that aren't appropriate for bronze can have major consequences. "For example, exposure to chloride—common around pools and a favorite 'cleaner' for some—will cause a damaging corrosive tarnish called bronze disease that will pit and eventually destroy the metal," Roberts warns. "Pressure washers have also been used by countless well-intentioned individuals to 'clean' bronzes. It is entirely unnecessary and could possibly damage the patina." He maintains that the best approach is the simple one detailed above: "Once you start adding metal polish or solvents, the results can be disastrous."
Roberts says to follow your natural instincts when it comes to your bronze pieces. "If you have concerns about cleaning your household bronzes, don't hesitate to contact a professional for guidance and guaranteed outcomes," he says. "They will—at the very least—help you make sure you are on the right track or provide you with more advanced solutions which they can execute for you." And for some items, especially those that were huge financial investments or carry sentimental value, it's always worth calling in an expert.