The solid, green layer on weathered copper consists of copper carbonate and copper sulfate. The water vapor and other substances in the air react with the surface of the untreated metal. The green barrier layer protects the underlying copper sheet from corrosion, similar to the rust on Corten steel. The process can take up to ten years and depends on the respective air and weather conditions. Oxidized copper is very strong, robust, almost indestructible and does not require chemical protective coatings.
The difference between copper patina and verdigris
A similar coloration as copper carbonate has the so-called verdigris, which is why the two are often confused. Verdigris, more specifically copper acetate, however, does not provide protection like the patina, but is moderately toxic. It is formed by the reaction of copper with acid - for example, when vinegar is stored in copper vessels. Verdigris is used as a color pigment and as a fungicide. Grünspan has no business on house facades or in the interior.
Anyone who chooses a copper façade has to expect that the color will continue to change over the years. This should be considered in the overall aesthetic picture.
The interior should match the material and the resulting patina. It is best to choose a neutral palette, as the color streaks from bronze to green are exciting enough.
You do not have to wait ten years to create the typical green barrier on copper. You can also accelerate the weathering - by sweeping the surface with substances that react with copper.
Primer, consisting of 1.3 percent ammonium chloride (sal ammoniac), 0.6 percent potassium hydrogen oxalate (clover salt) and 98.1 percent water also bring the desired effect. Within a few days, a patina is formed - for a more intensive result, the surface is smeared several times.
Due to its long-lasting, robust, flexible and weather-resistant material composition, copper sThey are often used for roofs. That is why it is mainly used for domes and elaborate roof geometries of churches. In addition, no moss is formed on the roof, and it hardly needs to be maintained.
Not everyone can afford copper and not everyone wants a wall in the apartment whose colors are constantly changing. As a solution to the problem, the industry has developed artificial effect paint, which is available in every hardware store or creative market. This is painted on any metal background, so that an imitated copper patina is created. In this way you can accurately determine the color streaks and the degree of green color and visually adapt the room concept.
Weathered copper is a popular vintage or shabby chic look. In this bathroom, the color of the washbasin matches the weathered copper tub, which serves as a sink.
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