Metal, Processes


The technique of applying a thin surface layer of one metal over another for decorative, aesthetic, or anti-corrosive purposes. Plating may be applied by a number of different means –
Diffusion bonded plating
Diffusion plating involves bringing the plating metal into intimate contact with the metal to be coated at elevated temperatures, by application of pressure or by mechanical working. The main use of this technique was for the production of Sheffield Plate – silver-covered copper sheet. Diffusion bonding was also used to produce the mokume multi-layer decorative metals used in Japan.
Dip or Hot Dip
In this technique the objects to be plated were dipped in a hot bath of the molten plating metal. This technique was used in the Iron Age to simultaneously plate and braze iron horse fittings rings; examples of this technique have been found at Gussage All Saints and Maiden Castle in Dorset, and Yarnton in Oxfordshire.
Other examples of hot dipping to protect iron sheet from corrosion are tin plating and zinc-coated galvanized iron
Electroplating uses an electric current to deposit the metal from solution on to the object to be plated, which acts as the cathode of the cell. The process was invented by Weiner Siemens in Germany, in 1842. His brother, Karl Wilhelm, introduced the process to Britain in 1843, where he sold it to James Elkington. This new electro-plating industry rendered the Sheffield plate industry obsolete by the latter part of the 19th century


A method of putting a thin layer of high carat gold on a less expensive substrate. This includes a number of methods that are given in more detail in the section on gilding – Depletion gilding, Foil gilding, Leaf gilding, Mercury or fire gilding.
Vapour deposition
A modern technique in which the object to be plated is put in a vacuum chamber and the metal is thermally vaporized and deposited on the surface as a thin film. Widely used to deposit aluminium on a wide variety of surfaces.
In this technique the metal object to be coated was fluxed and heated. The rod of the plating metal was rubbed over the areas to be plated. This technique was typically used for the decorative application of low melting point ‘white’ metal alloys.