Chemicals used in the patination process include, acid chloride, acid sulfate, ammonium chloride, hydrochloric acid and ammonium sulphate. The techniques used are subject to time, humidity, surface preparation and several other variables. Chemically inducing patina is a demanding process which requires a lot of craftsmanship and experience. This manual process of patination usually referred to as finishing, the product gains a particular look, color and feel. Metalworkers and artists deliberately add patina to the original copper body to reap the benefits of a patinated surface. The other type of patina is intentional patina. However, they adhere to the underlying copper surface. Copper patina is a very thin layer and ranges from 0.05 to 0.07 mm in thickness. As the process continues, the sulfide films are transformed into sulfates which are blue green or gray green. After a few years, cupric sulfide conversion occurs which makes the surface to darken and become brownish. ![]() Copper reacts with atmospheric oxygen to form copper oxide, copper oxide films become noticeable within the first six months of exposure.ĭuring the initial stages, the patina film formation is uneven, however, after nine months, the layer thickens and becomes even. Natural copper patination process begins immediately copper is exposed to the environment. The color changes are also gradual from salmon pink, orange, red, blue, green and purple, until a thick light green or blue green color is finally formed. In the natural patination process, copper undergoes several processes until a unique patina is formed. Natural Copper PatinaĪlso known as unintentional patinas are formed as a result of exposure of copper to oxidizing environment. There are two main types of patinas, natural patinas and applied patinas. The color of the patina formed can be either green or blue depending on the composition of copper and the chemicals that lead to patination. In urban areas, where the environment is endowed with sulfurous acid rain, the copper patina formed is mainly composed of sulphide and sulphate compounds. In clean environments such as rural areas, natural patina is formed by a slow chemical reaction that leads to the formation of copper carbonate. The nature of the patina formed depends on the environmental conditions surrounding the copper body. ![]() Formation of copper patina makes a body to lose its original color and texture and forms a bluish or a greenish surface. The process by which a patina is formed is known as patination. Natural oxidation of copper occurs as a result of exposure to atmospheric elements such as acidic rain, carbon dioxide, oxygen and other sulfur bearing compounds. Copper patina is a thin layer that forms on the surface of copper as a result of natural oxidation or chemically induced.
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