Vitreous enamel coatings metal preparation

Porcelain enameling. This is the entire process of applying a fused vitreous enamel coating to a metal basis material. Usually this includes metal preparation and coating operations.3-7... 

Vitreous enamel is normally applied to the prepared metal or over a ground-coat by spraying or dipping. Alternative wet techniques are used, of which the most common has been electrostatic wet spraying. Electrophoretic deposition from the slurry has been found to be highly suitable for some components. 

Copperhead. A fault (reddish-brown spots) liable to appear in the ground-coat during vitreous enamelling the spots are exposed areas of oxidized base metal. Causes include boiling from the base-metal, inadequate metal preparation, very thin application of enamel, and the presence of acid salts in the enamel slip. 

Scaling. Preparation of the base-metal for vitreous enamelling by heating it (often in an atmosphere of acid fumes or of sulphur gases) to form a surface coating of oxide - scale - which is subsequently removed by pickling (q.v.). 

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