Composition of Enamel & Enameled Wares
Enameled ware is sheet iron or steel coated with a glazed material which protects
the iron from rusting. This coating is not actually united with the iron as
in the case of tinned ware, but is fused or " fired " on so
that it will withstand ordinary usage. The foundations are made by the methods
described in the preceding chapter. The foundations must be firm and unbending
or the enamel will chip off when the article is bent and expose the iron to
action of rust. In time this action will undermine the entire covering.
Composition of Enamel
The hard, smooth coating of enamel is a form of glass, and like glass is composed
chiefly of silica, or sand, combined with feldspar, potash, soda, borax, and
some substance to produce the required color. The proportions vary in different
manufactories and are carefully guarded trade secrets.
There is, however, one very striking difference between the ingredients of
glass and those of enamel. Glass often contains substances, like arsenic, which
are perfectly harmless so long as the article is not subjected to heat, but
which would be poisonous in cooking utensils. Such materials are not used at
all in enameled ware.