Enamels and enamelling; an introduction to the preparation and ...

168 ENAMELS AND ENAMELLING.
red heat, at which temperature the glaze fuses. When properly
applied the glaze sticks very firmly to the metal and effectually
resists all external influences. Though excellent for iron pipes,
for which such a power of resistance is desired, this process
termed by its inventor " Emaille de fer contre-oxyde" is too
expensive for general use.
EMAILLE PLAQUE-VITRO-METALLIQUE.
Paris also rendered his method available to some extent
for artistic purposes by describing a process for durably
coating iron with other metals. With this object
the iron
surface, covered with glaze as above, is brushed over afresh
with gum, over which very thin sheets of metal foil (gold
leaf, silver foil, copper foil, platinum foil) are laid and fired.
Although in itself good, the metallic coating being ex-
tremely durable, the process is hardly likely to be of practical
use now that metal can be covered with and preserved from
rusting by nickel-plating.
ENAMELS FOR SHEET-IRON LOAF-SUGAR MOULDS.
A very useful enamel mass for sugar moulds, or indeed
any sheet-iron ware, is composed of
Green bottle glass
49 parts.
Fused borax 4 ,,
Litharge : 47
ENAMELLING TUBES FOR STEAM BOILERS.
Owing to the property exhibited by enamelled tubes
of iron, copper, or brass, of either entirely preventing the
deposition of boiler fur or else, by
reason of their smooth
surface, enabling the incrustation to be removed with ease,
the use of such tubes for locomotive boilers is continually
extending.
Their preparation is, however, attended with certain techni-