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

180 ENAMELS AND ENAMELLING.
is placed in a blast furnace having a strong draught and
heated by coke or charcoal. The gases from the hearth B
surround the muffle in the flue D and then escape to the
chimney E. While the pieces are being fired, the muffle is
closed by a fireclay plate F which is fitted with a peep-hole.
CLOISONNE ENAMEL.
This method of enamelling is peculiar, and furnishes products
of illimitable durability. As a rule it is practised on
copper or gold, and the procedure adopted by the artists of old,
and but recently discovered anew, is followed. The outlines
of the design to be carried out in enamel are marked on the
metal plate in such a manner that a very thin band of metal
remains between the edges of every two adjacent coloured
enamels, the space enclosed by the outlines being hollowed
out by the graver so as to leave a rough surface for the
enamel to adhere to. In the case of gold articles, the outlines
are also cut out of thin sheets of metal and welded on to the
base plate by heat.
The cells prepared in one or other of these ways
ire then
filled with a thick paste of enamel mass and lavender oil (or
water) which is fired in the muffle, and the operation is repeated
until the cells are completely full of the fused enamel, where-
upon the surface is ground and polished.
Similar results can be produced in a more direct way by
pressing the fused enamel into sharp-edged metal moulds,
setting the pieces in metal in a suitable manner, and finally
heating the finished article until the enamel begins to fuse,
grinding and polishing the surface when cold again.
The so-called "emaille champ-levee" is prepared by stamping
a design with steel dies on sheet gold and filling the recesses
with enamel, which is then fired. However,
of all these
methods, cloisonne is undoubtedly the best, on account of
the durability of the product.