The process of thinly coating sheets of iron or steel is known as tin-plating. It is mostly used to prevent rust and oxidation.
The primary use of tinplate is the manufacture of tin cans. The demand for beverage and food cans and for various other types of containers is growing very fast, resulting in a high increase of the demand for coated steel products.
In electro-tinning, the material (normally coils-strip) to be coated is transported thought an electrolytic cell containing a saline solution of one or more tin salts. The strip is connected to an electrical circuit, forming the cathode (negative) of the circuit while an electrode typically of the same metal to be plated (tin) forms the anode (positive).
When an electric current is passed through the electrical circuit, metal ions in the saline solution are attracted to the strip, forming a smooth and shiny surface being after briefly heated above the tin melting point.
Many of the tin-plated steel manufactured was then further electroplated with a very thin layer of chromium to prevent dulling of the surface from oxidation of the tin.
Nowadays, due to an interdiction preventing the use of chromium for health reasons are being used other types of temporary coatings in order to prevent oxidation and rust.