Enamels on Aluminium

Aluminium (aluminum) forms a thin transparent oxide film as soon as it is exposed to air. It does not oxidize any further when heated. This, in combination with its light weight, makes it very suitable for enamelling large panels.  I shall not elaborate on this any further, as - to my great regret -  the enamels suitable for enamelling aluminium were taken out of production by the Thompson enamel factory several years ago.