Hobbies And Interests
Patina
Patina is the more general of the two terms. In the case of antiques and collectibles, it's used to describe the subtly mellowed appearance of well-aged artifacts, whether they be coins, furniture, toys or anything else. A patina is usually caused by a mixture of age and handling. Age brings with it a degree of oxidation, and regular handling both polishes and wears away the original finish of an item. The oils in human skin, for example, will eventually give an ax handle a gentle sheen that can only be acquired by long use.
Patina on Metals
There are a very few metals that don't oxidize over time. Gold is one of them, and this has been part of the reason for its use in jewelry over the centuries. However, most common metals oxidize in varying degrees. In the case of iron and steel, oxidation results in rust, which is destructive and will rapidly destroy the metal if unchecked. Copper, brass, bronze, silver and other metals form a nondestructive layer of oxidized material that protects the underlying surface from the elements, while also providing an attractively aged appearance. This is a patina.
Verdigris
Verdigris is also a patina, but it's a specific one found only on copper and high-copper alloys. When copper is oxidized by exposure to the elements, it creates a surface patina that can be blue, green or gray. This is verdigris, notable among other metallic patinas for its rich and attractive color. The vivid blue-green of the Statue of Liberty is the best-known example of verdigris for Americans, though it is used as a decorative element in most parts of the country. Copper is often used as a decorative element on buildings and fixtures, purely for the verdigris that will coat it after a few years.
Verdigris as Pigment
Although verdigris normally develops on copper-containing metals over time, it can be generated deliberately by treating copper with acetic acid, the same kind that occurs in vinegar. Verdigris produced in this way was used for centuries as a green pigment for painting, because it is stable and won't break down when exposed to light. Unfortunately, it is also very toxic, and painters or paint makers who neglect hygiene can easily ingest enough to make them very ill.