The History and Legacy of Bronze Statues
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Bronze has been a cornerstone of artistic expression for thousands of years. Ancient civilizations, from the Greeks to the Romans, used bronze to create iconic statues that still inspire awe today.
Unlike other materials, bronze has a unique ability to withstand the ravages of time, making it a preferred choice for collectors.
Bronze vs. Marble: Durability and Longevity
Marble has long been associated with classical art, but it pales compared to bronze when it comes to durability.
While marble can crack and erode over time, bronze is incredibly resilient. Its resistance to weathering makes it ideal for outdoor statues, as it can withstand rain, wind, and even pollution.
For example, the Chimera of Arezzo, a bronze statue from ancient Etruria, has survived for over 2,000 years—proof of bronze’s enduring strength.
Bronze vs. Stone: Versatility and Detail
Stone statues are undeniably impressive, but they lack the versatility of bronze. The bronze casting process allows artists to create intricate details and complex designs that are nearly impossible to achieve with stone.
This is why bronze statues often feature lifelike textures, flowing drapery, and expressive faces.
Also, bronze’s malleability means it can be repaired or restored more easily than stone, ensuring longevity.
Bronze vs. Resin: Value and Authenticity
In recent years, resin has become a popular material for statues due to its affordability. However, resin lacks the authenticity and value of bronze.
Bronze statues are considered investments, often appreciating in value over time. They also have a premium feel that resin simply can’t replicate.
For collectors and art enthusiasts, bronze is the clear choice for its timeless elegance and long lasting quality.
Environmental Benefits of Bronze
In an era of increasing environmental awareness, bronze stands out as a sustainable choice.
Unlike resin, which is derived from petroleum, bronze is a recyclable material. In fact, many bronze statues are made from recycled bronze, reducing their environmental impact.
According to a study by the International Copper Association, bronze production has a lower carbon footprint compared to other materials, making it an eco-friendly option for artists and buyers.
Maintenance and Care for Bronze Statues
One of the biggest advantages of bronze is its low maintenance requirements. Unlike marble, which can stain, or resin, which can fade, bronze develops a natural patina over time that enhances its beauty.
Regular cleaning with a soft cloth and mild soap is usually all that’s needed to keep a bronze statue looking its best.
For outdoor statues, applying a protective wax coating can help prevent corrosion and maintain their luster.
Why Bronze Stands the Test of Time
Bronze’s unique combination of durability, versatility, and beauty makes it the ultimate material for statues and sculptures.
Whether you’re looking for a timeless piece of art or a durable outdoor sculpture, bronze offers unmatched quality and longevity.
Its ability to withstand the elements, capture intricate details, and retain its value over time ensures that bronze statues will continue to be cherished for generations to come.
Explore the Timeless Beauty of Bronze Statues
Ready to add a bronze statue to your collection? At Bronzeman.com®, we offer a stunning selection of bronze statues that capture the artistry and elegance of this timeless material. Browse our collection today and discover why bronze is the perfect choice for your home, garden, school, church or public space.
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The following guidelines provide general information on the characteristics and common uses of bronze and identify typical problems associated with the material. See also “Checklist for Inspecting Bronze Failures”.
Bronze is an alloy of copper which can vary widely in its composition. It is often used where a material harder than copper is required, where strength and corrosion resistance is required and for ornamental purposes. The variations in bronze (both in proportion and elemental composition) can significantly affect its weathering characteristics. “True” bronze is a combination of approximately 90% copper (Cu) and 10% tin (Sn), however there are three major classes or types of “bronzes” used in sculpture and construction. They are:
Traditionally, a copper alloy which contains zinc is a “brass”; a copper alloy which contains tin (not exceeding 11%) is a “bronze”. Bronze composition may vary significantly however, and contemporary bronzes are typically copper alloys which may contain silicon (Si), manganese (Mn), aluminum (Al), zinc (Zn) and other elements, with or without tin (Sn).
In its “raw” state, bronze is a semi-pink or salmon-colored metal; however it is rarely seen in its pure state. Bronze usually exhibits some patination or corrosion so that its color normally ranges from lime green to dark brown. Exposed bronze undergoes continuous change and progresses through several predictable “stages” of oxidation and corrosion. The stages of bronze corrosion vary in duration and time of onset, based on many factors, including:
Statuary bronze is typically used in outdoor sculpture. Its forms are almost limitless since it may be cast in any shape for which a mold can be devised. The most common types of forms include the human figure, landscapes, battle scenes, animals, weapons, decorative elements such as stars, rosettes, etc., and plaques.
For more information, please visit Bronze Animal Sculptures.
Architectural bronze is typically used for:
As a general rule, architectural applications seek to preserve the natural, highly polished “pinkish” finish of raw bronze, in contrast to the patination of outdoor sculpture/ornament. This is achieved by the frequent polishing and oiling of bronze/brass decorative and structural elements, or the application of clear lacquers which must be renewed on a periodic basis.
Bronze has good resistance to:
Bronze has poor resistance to:
Problems may be classified into two broad categories: 1) Natural or inherent problems based on the characteristics of the material and the conditions of the exposure, and 2) Vandalism and human- induced problems.
Although there is some overlap between the two categories, the inherent material deterioration problems generally occur gradually over long periods of time, at predictable rates and require appropriate routine or preventive maintenance to control. Conversely, many human induced problems, (especially vandalism), are random in occurrence; can produce catastrophic results; are difficult to prevent, and require emergency action to mitigate. Some human induced problems, however, are predictable and occur routinely.
Bronze, like cast iron, is a manufactured product. Copper is extracted from natural ores and alloyed with tin to create a metal which does not exist in nature. Many of the inherent problems relate to the normal physical process of the bronze “returning to nature”, i.e. to the most stable states of its components.
Additionally, most outdoor bronze is erected with a foundry applied patina of some type. The actual surface patina could be one of dozens of different composites as a result of the foundry applied finishes. Each of these finishes may react differently with the environment and result in different corrosion types and rates.
Regardless of which finish exists, the bronze will begin the deterioration process described below, where the surface will be subjected to the alteration of the patina through oxidation and sulfurization. Patinated and protected surfaces will resist the effects of exposure more than bare metal; therefore, such pieces will maintain their original appearance longer and exhibit changes more slowly.
Corrosion of one form or another is the chief cause of the deterioration of metals, including statuary and architectural bronze. The degree of corrosion which occurs, and the corrosion by-products which result, are affected by several factors including bronze composition or formulation, environmental conditions and adjacent materials.
While the composition of bronze does affect the rate of corrosion, it has been generally recognized that composition is one of the least significant factors in bronze deterioration. The existence of chemicals in the atmosphere, such as chlorine, sulfur, and nitrogen oxides, in the presence of moisture, is the most significant cause of bronze deterioration.
There are numerous causes and symptoms of corrosion, including:
The bronze corrosion process goes through five predictable stages. The specific results of each stage can differ due to combinations of atmospheric elements, bronze composition, patination, and other protective treatments such as waxing, oiling or lacquering. The five stages are:
Unprotected areas of raw bronze will oxidize, or combine with oxygen present in the air, resulting in a thin film of copper oxide along the surface of the exposed bronze. The resulting appearance is a flat, dark brown surface. The most common example to which most users can relate is the process of oxidation of a copper penny. The specular (shiny) finish of a new penny is familiar, as is the shift to the dark, red-brown finish as the surfaces oxidize over time.
This normal process of oxidation is a form of corrosion. The resultant oxide film is less reactive than raw bronze and forms a stable, protective barrier with a greatly reduced rate of oxidation.
Bronze also reacts with many atmospheric pollutants, especially sulfur compounds, which are normally found in the atmosphere as sulfur dioxide and hydrogen sulfide. Both are produced in industrial manufacturing processes. Concentrations of these gasses are generally greater in or near urban and industrial areas; therefore higher rates of corrosion can normally be expected in such areas. The initial symptom of sulfurization is the appearance of patches of light green primarily on exposed surfaces. This usually begins on horizontal surfaces which receive the greatest exposure to rains and water run-off.
A general layer of surface corrosion can eventually spread over the entire metallic surface, resulting in an overall bright green surface. The uniform green surface is often accepted by the general public, and others, as protective and the normal state of bronze. This is a misconception, and one which has probably resulted in the public acceptance of appearances which are actually symptoms of corrosion and deterioration. The sulfides and sulfates will continue to form in the presence of moisture and atmospheric sulfur compounds. The presence of green corrosion products on the bronze is always an indication of active corrosion. The pattern and result of this process will vary based upon several environmental factors such as wind, rain, pollutants, patina, and the nature of previous corrosion.
Differential weathering due to winds, rain and surface orientation can result in uneven corrosion with patterns of green streaking on a dark blackish surface.
The process of sulfurization is complicated by two factors, both of which result in aesthetically unacceptable appearances; appearances which are generally perceived as neglect and deterioration. Uneven black and green streaking of bronzes is one of the most disfiguring problems which can occur with bronze. Random dark (black) and light (green) streaks follow the contours downward, resulting in distracting visual patterns with no relationship to the form or texture of the surface of the work. The artistic details which give form and definition to the bronze become extremely obscured by streaking which results from two phenomena:
The streaking of bronze indicates a differential corrosion of the bronze which will be permanently disfiguring. Two different surface corrosion products are dissolving at significantly different rates. The geological analogy is the formation of canyons by the erosion of the land surface. Where such corrosion has already occurred, conservation techniques are likely to be required. Early indications of streaking should be given serious attention in the inspection process, and called to the attention of the Regional Historic Preservation Officer (RHPO) at the earliest possible time.
Bronze disease is the result of exposure to chlorine compounds which can come from any saline source, such as contact with saline soils, atmospheric pollutants or airborne salt spray near bodies of salt water. The chlorine reacts with the copper in bronze to form copper chloride. The primary symptom is pitting, and the process can proceed unchecked below apparently sound patinas, or protective coatings.
The copper chloride is relatively unstable and the only way to arrest the continuing corrosion is the complete removal of the chlorides using electrochemical methods. All such methods of chloride removal are advanced conservation techniques requiring the employment of a skilled professional.
Bronze is cast in a foundry process which consists of the pouring of molten bronze into a mould containing a central core. Frequently this core material is gypsum or plaster of Paris, and occasionally portions of the core are left inside the casting. It is possible for the core material to migrate through the casting wall over time and appear on the exterior surface of the bronze.
The removal and repair of core migration problems is not a maintenance procedure and will require an “existing conditions analysis” supporting a proposed conservation treatment. The RHPO should be notified of the problem following its identification. The most common symptom is the appearance of whitish spots, which gradually enlarge, in the bronze surface.
Corrosion of bronze, unlike that of natural stones, is in part an electro-chemical phenomenon. Points of negative electrical potential called cathodes and points of positive potential called anodes form on the bronze. In the presence of moisture, the corrosion process is driven by an electrical differential between the two points. This process can occur at a highly accelerated rate.
An electric potential can develop between both large and small areas. Atmospheric pollutants, especially chlorides, can be deposited on the surface of bronze. Tiny “islands” of corrosion can form, rapidly eroding/converting away the bronze metal and resulting in tiny voids or pits in the surface of the bronze. Pits may begin small and increase in size due to the continued electrochemical action and deposition within the pits. This may continue as long as moisture is present.
Pitting may be pinpoint or broad, as in patterns of deep etching created by differential erosion. (Also see: Bronze Disease)
Bird, or other animal, droppings may collect on the surface of bronze and (because of the acidic nature) may accelerate localized corrosion and deterioration. Droppings can also build up in sheltered areas, providing concentrations of damaging chemical agents of deterioration.
Galvanic corrosion, also known as dissimilar metal corrosion, occurs when two dissimilar metals are brought into contact with one another. One of the metals will corrode, and the other will remain intact. As an example, if bronze is brought into contact with iron, the iron will frequently begin to corrode. Galvanic corrosion is caused by an electric potential between two dissimilar metals in the presence of water or moisture, where the water’s electrolytes allow the flow of metallic ions from the more active metal, or the anode, to the more noble metal, or the cathode. The movement of these metallic ions represents a physical loss of metal from the metal being corroded. It can continue until the source metal is completely gone.
Below, thirteen construction metals are ranked according to their susceptibility to corrosion, from most to least susceptible, or from active to noble. This type of ordered list is called a Galvanic Series chart.
The rate of the transfer of iron from the passive to the active metal is determined by the difference in electrode potential between the two metals. Therefore, the farther apart two metals are in the list below, the more likely the active metal (higher on the list) is to corrode.
Galvanic corrosion typically occurs where dissimilar metals are used as connectors or parts of a building’s armature. It can be stopped by replacing the more active metal with a more noble metal such as stainless steel. When two dissimilar metals must be in contact with one another, the risk of corrosion can be substantially reduced by applying a coating to both of the materials but especially to the noble metal, or applying a sacrificial metallic coating that is more active than both of the metals.
The relative mass or sizes of the two metals in contact will also determine the rate at which galvanic corrosion occurs. As an example, in a bronze plaque with iron bolts, the bolts would corrode rapidly, but an iron plaque with bronze or copper bolts would exhibit a much lower, almost negligible, amount of galvanic corrosion as a result of its contact with the bolts. Therefore, bolts and other fasteners should be made of more noble metals where possible.
Erosion or “wearing away” of metal from the surface may be due to natural or environmental factors, or due to man-induced factors such as excessive handling or rubbing. Erosion due to human contact is by far the most serious problem, but erosion can occur due to the abrasive action of wind-driven pollutants.
Natural erosion will be a slow process and one which is, therefore, difficult to detect. It will be most obvious on outdoor bronze or in exposed locations. Industrial settings and areas where there are higher concentrations of airborne particulates, which can act as abrasives, also offer the possibility for higher rates of erosion. Natural, wind-driven abrasion will be generally so slow that it will be most apparent when comparing different exposures/orientations of bronze which has been in service for long periods. The differential loss of detail between protected and exposed surfaces will begin to be apparent over many years. Examination for this differential weathering should be part of any inspection.
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