Īrchaeologists also use the term patina to refer to a corticated layer that develops over time that is due to a range of complex factors on flint tools and ancient stone monuments. Patina also refers to accumulated changes in surface texture and color that result from normal use of an object such as a coin or a piece of furniture over time. In common parlance, weathering rust on steel is often mistakenly referred to as patina. On metal, patina is a coating of various chemical compounds such as oxides, carbonates, sulfides, or sulfates formed on the surface during exposure to atmospheric elements ( oxygen, rain, acid rain, carbon dioxide, sulfur-bearing compounds). They may also be aesthetically appealing. Patinas can provide a protective covering to materials that would otherwise be damaged by corrosion or weathering. The patinas on leather goods are unique to the type of leather, frequency of use, and exposure. Patina ( / p ə ˈ t iː n ə/ or / ˈ p æ t ɪ n ə/) is a thin layer that variously forms on the surface of copper, brass, bronze and similar metals and metal alloys ( tarnish produced by oxidation or other chemical processes) or certain stones and wooden furniture (sheen produced by age, wear, and polishing), or any similar acquired change of a surface through age and exposure.Īdditionally, the term is used to describe the aging of high-quality leather. The external layer has been weathered by moisture and rain, leading to the oxidation of copper. Pre-colonial copper coin formerly used in the Copper Belt ( Democratic Republic of the Congo and Zambia).

Patina green color