that is streaky with black and green corrosion products ; it also leaves pits and exposes hidden defects on the surface . Rather than exhibiting a reflective surface with an aesthetically applied patina , sculptures become muddy and difficult to read as a consistent whole . Left untreated , the sculpture can continue to corrode and much of the original surface ( tool marks , fine details ) can be lost . detail , the object is patinated . Though this word “ patina ” evokes the image of a green surface ( such as is observed on the Statue of Liberty , which is made from sheet copper ), this is not usually the case for 19th century bronze statuary . The majority of bronze objects from this period were originally patinated to a brown tone . The patina is formed by applying chemicals to the surface of the bronze along with the application of varnishes and waxes . There are some exceptions to this ; bronzes are occasionally gilt or polished and can be patinated in a variety of colors . ( As noted in the treatment section , it is important to research the object thoroughly before conducting a treatment .)
Exposure to a polluted outdoor environment can cause damage to the surface of a bronze object . Acid rain and snow cause applied surface coatings to degrade and cause numerous reactions with the metals in the alloy . This results in a bronze surface
Other factors can also damage bronze objects . Well-meaning attempts to clean the surface using acids and sand blasting can cause significant damage to the surface and exacerbate the corrosion process . Repairs and support systems made from ferrous metals can cause the bronze to become unstable , as the ferrous metal loses integrity when in contact with the bronze . Vandalism can come in many forms including graffiti , removal of accessories such as swords , rifles , straps and spurs . We have treated numerous sculptures that have been completely knocked off their pedestals and the damage has been significant . Close proximity to trees and landscaping can cause damage from falling limbs , root structures can cause dislodged pedestals , moss and lichen can form on the sculptures and pedestals and poorly navigated mowing equipment can wreak havoc on stone pedestals or sculptures .
Bronze objects , whether they are figures , reliefs , plaques or architectural elements such as lampposts , doors or building facades should always be looked at as unique . Treatment plans should be specifically designed based on the condition , environment and history of the object . The steps ( outlined at end of article ) can be used as a starting point when determining the best path for treatment .
We find that once the treatment is complete people are amazed by the subtleties that can be noticed in the form and renewed detail that was lost prior to treatment .
An important part of any treatment of bronze objects is the development of a maintenance plan . Maintenance includes washing the surface with an anionic detergent , touching up or repairing the coating as needed and re-waxing the surface . The
102 BSLA