Patina

Patina (Italian patina " thin layer ", " varnish ") is a caused by natural or artificial aging surface ( texture and color ).

• 2.1 patina of gold and silver
• 2.2 patina on copper 2.2.1 Conditional emergence weather
• 2.2.2 Artificial generating

Basics

The patina is a layer (dust, aerosols ) and the reaction products of these materials results from the weathering products of the surface, sedimentation of suspended particles in air:

• Oil paintings patina because the varnish which is new as far as possible neutral color - transparent, yellowed by oxidation ( which derives from the Italian name ). For the color effect of the image is disturbing.
• A sculpture that is exposed to the influences of the weather, obtained by chemical or corrosive influences a unique, often very attractive interface. Here, the patina is desired, as long as it is not unsightly.
• Wall murals are exposed to strong patination. A particular problem is that the fresco, because of the manufacturing principle over time according to the color layer, with the patina einsintert. You can therefore may no longer be removed without the fresco (or his guardian ) to destroy.

The patina is considered as evidence for the age of an object. This has two effects:

• In restoration
• Patination as artificial aging.

The patina in the restoration

In the modern restoration of the patina is counted with the original substance, as it documents the object history as few other aspects of conservation status. From a concept of " Erstrahlens in a new light ", the historic preservation distanced, still cleaning an object in the context of the restoration is essential. In what way the patina will be so received, must be weighed in each object.

Patinate

Because the patina of the age of a surface stresses so they can on one hand be used as a means of artistic expression, to take an object that hard " New ", or in the forgery to cover up the new.

• In contemporary art, patina is often used to emphasize the artistic effect of a sculpture. This wins a sculpture of plasticity, the surface becomes more vivid.
• The patination of a replica for fraudulent purposes, such as to increase their value, it makes for forgery.

For patination, the surface is often covered with a layer of paint or stain and then further processed with different techniques ( scraping, brushing, polishing, etc.). Depths are usually accented with a darker color, while the highs are highlighted by a bright color scheme. Particular, the following materials are used for the production of artificial patina: oil glaze, acrylic, wax, alcohol glaze and color pigments.

Patination as "artificial aging " is also common in stage design, costume making and model making.

Special cases of patina

Patina of gold and silver

The patina luster gold plating and silver plating differs from it: The natural patina, especially gold, can be artificially produced little, but neither gold nor silver may be dissolved. Therefore, metal coatings can patinate only in oily technology. Which is applied in the restoration with the renovation of a gilding, where the fresh surface would be overly intrusive.

Patina on copper

Patina are copper (carbonate sulfate chloride ) hydroxide mixtures, urates, or salts of other organic acids ( basic copper compounds ) and form, for example, copper- roofs that are exposed to the weather (corrosion), or by etching of copper and copper alloys such as bronze. Contrary to popular belief, these are usually greenish layer is no verdigris, because this is the common name for copper.

Weather Conditional emergence

Today, the natural patina consists mainly in layer lattices ( brucite - type) crystallized basic salts. These include the basic copper sulfate, but less carbonate and chloride. It occurs gradually in the atmosphere under the influence of substances ( CO2, SO2, etc., near the sea and chlorides ), which are included in addition to water vapor in the air. An example of weather-related Kupferpatinierung is the Statue of Liberty, as many copper- covered spiers are green thanks patina.

Artificial generating

The patina can be produced artificially by patination. For this purpose, there are different methods. Can be the copper

• Put together with a bowl of hydrochloric acid and marble ( carbon dioxide evolution ) extended periods of time under a glass bell.
• Alternately for twelve hours diving in ten percent ammonium sulfate solution and allow to air dry.
• With a solution containing 13 grams of ammonium chloride and 6 grams of salt in a liter of water clover, brush.
• Brush with a solution of liver of sulfur ( Kaliumpolysulfid ) in water. It forms black copper (II ) sulfide.

Other metal Patinae

Iron alloys, there is the method of Brünierens in which a dark layer is placed over the metal, in order to protect it or to give it an antique look.

Feuerpatinierung of brass see also: Ikora.

Aluminum can be brownish patina by brushing with oil, for example olive oil or linseed oil, and then heating up to 400 ° C.

Teepatina

During brewing of tea in a teapot is formed a common brown coating on the inner walls, which is also called patina. In professional preparation as well as in tea ceremonies, the teapot is washed only with water without detergent, so that the pot does not absorb any foreign flavors. Often those Teepatina will leave it at that.