Body : A shiny new penny carried in a pocket will tarnish; a bronze bracelet buried for a thousand years will develop a crust and a statue by the sea, if uncared for, will green; these changes are all the result of corrosion. The way in which a piece of bronze corrodes is characteristic of the environment it has been a part of. This is not to say that the object’s unique structure does not contribute to its degradation, however, objects produced identically will corrode differently in different environments.
Bronze is a generic term for a copper alloy. It is an intimate blend of copper with one or more metals or non-metals (Street & Alexander 1995, p36). Copper alloys in an urban external environment fall mainly into two categories; statues and monuments including art works and commemoratives features and architectural features on buildings such as doors, window frames and lamps. For the purposes of this report, these two categories of bronze will be the focus.
An urban outdoor environment has certain characteristic elements; pollution from the burning of fossil fuels via cars, factories and houses, human contact and exposure to the weather. This environment is distinct from others such as marine where the salt content of the air plays a more dominant role or burial environments where the pH of the soil and soil’s content will make its mark. Even a museum environment contains pollutants given off from materials making up display cases, the outdoors and from its visitors.
Corrosion is an important topic; not least because in an urban environment it is can be looked upon with rose tinted glasses; common phrases associated with corrosion “ the monument has aged; the door has weathered; the statue has developed a patina”. Aesthetic preferences aside, understanding the science of what is occurring at the surface of our bronze features provides us with a romanticised view, which is valuable to the conservator for making treatment decisions, the custodian who must make decisions about the care taking of these pieces and the public who hope to enjoy them long into the future.
The author has been restoring bronze antique for several years. It has done
monument restoration,
monument cleaning and restoration activities for antique dealers, Interior decorators, Museums and Collectors. For getting more information, access www.antiquebronze.co.uk.
