Bronze Sculpture 101: Understanding Patina

As stated on wikipedia:

Patina (pronounced /ˈpætənə/ or /pəˈtiːnə/) is a film on the surface of bronze or similar metals (produced by oxidation over a long period); a sheen on wooden furniture produced by age, wear, and polishing; or any such acquired change of a surface through age and exposure. On metal, patina is a coating of various chemical compounds such as oxides or carbonates formed on the surface during exposure to the elements (weathering). Patina also refers to accumulated changes in surface texture and colour that result from normal use of an object such as a coin or a piece of furniture over time.

Patinas are restricted to exposed surfaces and are fragile (that is, they can flake off). One reason bronze is so highly valued in statuary is that its patina protects or passivates it against further corrosion. This natural patina is solid and seldom shows a tendency to flake. Brass is also resistant to corrosion, but it is, in the long run, not as attractive since local pitting shows against the shiny background.

The green patina that forms naturally on copper and bronze is often mis-named verdigris and usually consists of a mixture of chlorides, sulphides and carbonates. copper carbonate or copper chloride. Atacamite is another name for the patina compounds. Verdigris can be produced on copper by addition of vinegar (acetic acid) - such a verdigris is water-soluble and will not last on the outside of a building like a "true" patina.

One example of a patina is a green surface texture created by slow chemical alteration of copper, producing a basic carbonate. It can form on pure copper objects as well as alloys which contain copper, such as bronze or brass.

Artists and metalworkers often deliberately add patinas as a part of the original design and decoration of art and furniture, or to simulate antiquity in newly-made objects.

A wide range of chemicals, both household and commercial, can give a variety of patinas. They are often used by artists as surface embellishments either for color, texture, or both. Patination composition varies with the reacted elements and these will determine the color of the patina. For copper alloys, such as bronze, exposure to chlorides leads to green, while sulfur compounds (such as "liver of sulfur") tend to brown.


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Buying Bronze Sculpture 101: Patina or paint?

When you read some of our descriptions you'll often notice that we mention that a piece is colored with an all natural "patina" finish. You may ask yourself, "What the heck is a patina?" Bronze is made up of a few metals, mainly copper, and some other alloys. These metals, when heated, react in a certain way to different chemicals and acids which produce a certain color. The real look of a bronze sculpture that has no patina is that of a new penny. The "traditional" look of bronze statues, that dark brown coloring like our wild horse, is actually a patina that was applied to the heated metal to create the color. Bronze can be colored in several shades using this chemical reaction process. Most often they are greens and browns. If you want your bronze statue or fountain to have a more realistic look,like our Mermaid with 8 dolphins, traditional paint must be used. An oil based paint, like automotive grade, gives a shinier, almost porcelain appearance, whereas acryllics will be more of a matte finish. In both cases a protective coating is applied to maintain the look for a long time.
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Bronze Sculpture Statue Patina Application Process

This video was taken on our last trip to the foundry. It shows part of the patina process for the bronze statues and sculptures we have. It's a very cool process as you can actually see the metal change before your eyes. People don't always realize the amount of work that goes into creating these pieces but they are all individually hand colored. Just another reason our pricing is so fantastic. You just won't find better prices for truly hand made sculptures or statues.