Patina

What is Patina?

When a substance or material is exposed to air for a long time, it shows some changes in the properties. Like rust, as in case of iron. This may be developed due to the absorption of oxygen molecules by these substances through the atmospheric air or moisture. This process is called oxidation. In case of copper, oxidation results in the formation of green color coating in it. This is called patina. This may not damage the copper but formed like a coating on the surface of the copper. This may be classified into two types as acquired patina and applied patina.

Acquired patina:

The green patina that naturally forms on the surface of the material is called Natural / Acquired patina. This may takes place several days to form and the formation is due to weathering processes. This is commonly called Verdigris. The statue of liberty in the USA is the best example of acquired patina.

Applied patina:

Artists and paint workers deliberately add patinas for decoration or to stimulate antiquity in newly made objects. This is called distressing. 

Repatination:

In case of antiques (materials and furnitures of aesthetic value), a range of views are held on the value of the patination and the replacement if damaged, known as repatination.