Electrotyping

Galvanoplastics are sculptures made ​​of metal, which are not produced by casting, but in the subsequent electroplating a plastic either remaining or after galvanization remote model. They are due to their low wall thickness comparatively light, yet stable. About their artistic value is disputed to this day. The creation of such sculptures - although that term is controversial here also - can offer artistic freedom; much more common, however galvanoplastics are reproductions of a work of art or any other template.

Production

Basically, two types of production can be distinguished: The hollow and the Kerngalvanoplastik. The main difference is that the Hohlgalvanoplastik consists solely of a slightly thicker ( copper ) shell. An artist's signature would emerge slightly raised with her. When Kerngalvanoplastik would such a contrast cut into it directly in the positive form, so that it is slightly after galvanizing below the surface level.

The Hohlgalvanoplastik

For producing a negative mold of the model Hohlgalvanoplastik a is either produced at the later the copper can be deposited. Or a positive mold, e.g., of wax, plastic foam, O. A., after its surface has been mainly made ​​conductive, electrolytically coated with a thin metal layer, and then destroyed either by dissolving (for example, plastics with acetone ) or by melting (eg wax in the hot water bath). The thickness of galvanizing layer, and thus the wall thickness of the finished sculpture is between 4 and 8 mm.

The Kerngalvanoplastik

When Kerngalvanoplastik is a plaster copy of the original model, ie, a positive mold made ​​. For better stability, it is provided with iron reinforcements. Made conductive, a very thin layer of 0.3 deposited in the plating bath - 3 mm of pure copper, which surrounds the plaster. The plaster remains inside the plastic.

Electroplating

First, the desired shape is modeled from a suitable material, then the surface of silver ink, graphite or graphite iron Leitspray or powder is made superficial conductive. It is important that at least one body is not coated. The article is now hung with conductive wires in an electroplating bath. The dissolved metal in the bath is then reflected under current flow to the leitendgemachte mold surface, as this acts as a cathode which emits electrons. The result is a metal layer. According to need a fairly strong layer of copper is first applied, usually stronger and finer followed by corrosion layers, for example, nickel, silver or gold. Were - deliberately or accidentally - points on the surface made ​​non-conductive, so has the plastic later in these places holes. At the end of the electroforming is still carefully cleaned, polished or possibly reworked.

History

Basis of all galvanoplastic preparation was the research of the anatomy professor Luigi Galvani, the end of the 18th century made ​​discoveries about contacts between copper and iron. He allowed the electroplating. This is an early type of electroplating, which allowed to coat conductive metals such as gold or silver. Starting in 1836 & Co. was gold plated tableware in England in the silverware factory Elkington, ie electroplated. 1837 Moritz Hermann von Jacobi invented the method by which one can electroplated copper thanks to an electrically conductive graphite layer non-conductive materials such as wood or plaster. With the 1867 developed by Werner von Siemens dynamo finally enough electricity could be produced for the first time to apply the electroplating industry also. In order to produce large objects galvanoplastically, later developed especially Rudolf Christian Böttger in Frankfurt an improved method.

Crafts

Shortly after the development of the method it was made available for the purposes of arts and crafts. First, however, were only small items, for example, flowers, butterflies and other gimmicks, galvanized. In 1853 let himself Emperor Napoleon III. produced galvanically plated knife. In 1890 a subsidiary factory of the WMF had perfected the technique of electroplating. At the beginning, ie from 1890 to 1902, presented electrotype department WMF produces mainly small statuettes. These were mainly to a maximum of one meter high copies of antique statues that served as room decorations. From 1902 grave figures were then produced predominantly, especially angels, but also figures of Christ and others., You look attractive and precious from, but can be purchased for a fraction of the price of a stone sculpture or bronze sculpture. In the German silverware industry electroforming has been applied since the 1870s to implement artist models for honorary gifts or centerpieces in silver Furthermore galvanoplastics metal finds suitable for the production true to the original copies of archaeological such as coins, jewelry, and metal tableware. Many art museums acquired in the second half of the 19th century next to plaster casts also galvanoplastics for didactic collections.

In 1948 the present Tübingen Fountain of Neptune was produced as electroforming of the WMF.

Technology

In the technique extremely thick-walled galvanoplastics in mold be used for injection molding of plastics. Often these galvanoplastics consist of a nickel -cobalt alloy high strength, which is deposited from a solution of their sulfates. If the prototype is not electrically conductive, it is made conductive by sputtering or by vapor deposition of metal in a high vacuum.

In microsystems technology, among other things Lithographically - galvanic molding ( LIGA ) is used, which uses the high accuracy of the electroforming.

Means galvanoplastic molding of models are eg ledergenarbte forms produced (from leathered with genuine leather master models ) for the production of a slush skin. Other technical applications of electroforming are, for example, the construction of waveguides in the High Frequency Technology (mostly copper ) or the manufacture of extrusion dies for vinyl LPs or CDs ( nickel ).