Electroplating
Electroplating are sculptures made of metal that are not produced by casting , but rather by electroplating a model that either remains in the later plastic or is removed after electroplating. Because of their small wall thickness, they are comparatively light, but still stable. The creation of such sculptures can offer artistic freedom; Electroplating is much more common, however, as reproductions of a work of art or another model.
Manufacturing
Basically, two types of production can be distinguished: Hollow and core electroplating. The main difference is that the hollow electroplating consists exclusively of a slightly thicker (copper) shell. An artist's signature would stand out slightly raised on her. In the case of core electroplating, on the other hand, this would be cut directly into the positive form so that it would be slightly below the surface level after electroplating.
The hollow electroplating
To produce a hollow electroplating, either a negative form of the model is made, on the inside of which the copper can be deposited. Or a positive form, e.g. B. made of wax, foam plastic, o. is coated with copper on the outside and then removed from the inside of the finished plant. For life-size sculptures or larger, the thickness of the galvanized layer and thus the wall thickness is usually between 4 and 8 mm. The detachment of the model can be done with plastics such. B. done with acetone or by melting out wax molds.
The core electroplating
With core electroplating, the model is made (approximately) the size of the finished plastic, i.e. as a positive form. The model is usually made of plaster of paris, which can be reinforced with iron for better stability. Made conductive, a thin layer of 0.3 - 3 mm made of pure copper is deposited in the galvanic bath, which surrounds the plaster of paris. The model remains inside the plastic.
Electroplating process
First, the desired shape is modeled from a suitable material. Then the surface is made superficially conductive with conductive silver lacquer, graphite or graphite-iron conductive spray or powder . It is important that at least one area has not been coated. The positive form is then hung with conductive wires in a galvanic bath or the electrolyte is poured into the negative form.
The metal dissolved in the bath is deposited under the flow of current on the conductive surface of the mold, since this acts as a cathode that emits electrons. This creates a metal layer. Depending on requirements, a sufficiently thick base layer made of copper is applied first, which is then coated with more corrosion-resistant and decorative cover layers, e.g. B. is plated from nickel , silver or gold . If parts of the surface were made non-conductive - deliberately or accidentally - the plastic will later show holes in these places. At the end, the electroplating is carefully cleaned, polished and, if necessary, reworked.
history
The basis of all galvanoplastic production was the research of anatomy professor Luigi Galvani , who made discoveries about contacts between copper and iron at the end of the 18th century. With this he made electroplating possible. This is an early type of electroplating, which allowed conductive metals with z. B. to coat gold or silver. In Italy it was further developed by Luigi Valentino Brugnatelli . As early as 1836, tableware in the Elkington & Co. silverware factory in England was galvanically gilded, i.e. H. electroplated. In 1837 Moritz Hermann von Jacobi invented the process with which, thanks to an electrically conductive graphite layer, non-conductive materials such as wood or plaster can be electroplated with copper. With the dynamo machine developed by Werner von Siemens in 1867, it was finally possible for the first time to produce enough electricity to use electroplating technology on an industrial scale. In order to manufacture large objects by electroplating, Rudolf Christian Böttger in particular later developed an improved method in Frankfurt am Main .
Handicrafts
Shortly after the process was developed, it was made usable for the purposes of the arts and crafts. Initially, however, only small objects, such as flowers, butterflies and other gadgets, were electroplated. As early as 1853, Emperor Napoleon III. Manufacture electroplated knives. From 1890 a subsidiary of WMF had perfected the technique of electroplating. At the beginning, i.e. from 1890 to 1902, the electroforming department of WMF mainly produced small statuettes or wall medallions. These were mainly copies of antique statues or custom-made models that were no more than one meter high, which were used as room decorations, but also to decorate churches and were touted in church publications as inexpensive artistic works of art. Examples for 1891/92 can be traced in the Protestant Sebastian Church in Schwabbach and in the Protestant town church in Geislingen . From 1902, grave figures were mainly produced, especially angels , but also figures of Christ and the like. a. They look attractive and valuable, but can be purchased for a fraction of the price of a stone or bronze sculpture. Electroplating has been used in the German silverware industry since the 1870s to make silver artist models for honorary gifts or centerpieces. Electroplating is also suitable for the production of true-to-original copies of archaeological metal finds such as coins, jewelry and metal tableware. In the second half of the 19th century, many arts and crafts museums also acquired plaster casts as well as electroplating for didactic collections.
In 1948 WMF manufactured today's Tübingen Neptune Fountain as an electroplating.
technology
In technology , extremely thick-walled electroplating is used in mold construction for the injection molding of plastics . These electroplating often consist of a nickel - cobalt alloy of high strength, which is deposited from a solution of its sulfates . If the original form is not electrically conductive , it is made conductive by sputtering or by vapor deposition of metal in a high vacuum .
In microsystem technology , among other things, lithographic-galvanic molding ( LIGA ) is used, which uses the high accuracy of galvanoplasty.
By means of galvanoplastic molding of models z. B. leather-grained forms (from master models covered with real leather) for the production of a slush skin . Further technical applications of electroplating are z. B. the construction of waveguides in high frequency technology (mainly made of copper) or the production of press dies for records or CDs (made of nickel).
literature
- Meißner, Birgit / Anke Doctor: Electroplating - History of a technology from the 19th century , in: Bronze and electroplating. History - material analysis - restoration (PDF; 5.8 MB), ed. v. State offices for the preservation of monuments in Saxony and Saxony-Anhalt, Dresden 2001, pp. 127–137.
- Thormann, Ellen / Barbara Leisner / Helmut Schoenfeld: Lots of angels. Electroplating at the Ohlsdorfer Friedhof , series of publications by the Förderkreis Ohlsdorfer Friedhof e. V., Vol. 8, [Hamburg] 1997.
- GL von Kreß : Electroplating for industrial purposes: results of twenty-six years of experience . Frankfurt a. M. 1867 ( digitized version )
Web links
- Electroformed copies of antique metal objects
- Birgit Meißner, Galvano, Galvanoplastik, in: RDK Labor (2019)
supporting documents
- ↑ Ludwig Darmstaedter (ed.): Handbook for the history of natural sciences and technology In chronological representation , 2nd edition, Springer-Verlag Berlin 1908, p. 427 online
- ↑ Johannes Merz: The good shepherd ; Editorial article Christliches Kunstblatt; Born in 1894, issue 3, Stuttgart 1894, pages 34–37
- ↑ Eva Heer: Dusty on a stage. The show in the art cabinet shows pieces from the electroplating factories ; in: Südwestpresse / Neue Württembergische Zeitung, article from February 8, 2014, Göppingen / Ulm 2014 - see [1] , last accessed on July 15, 2020
- ^ Alfred Löhr: Electroplating in the Bremen silver goods industry . In: Bremen is getting light. 100 years of living and working with electricity. Bremen 1993, pp. 266-273