n a ground of leaf gold. Any of them may
be used with good seed-lac varnish, for reasons already given. Equal
parts by weight of rosin, precipitated rosinate of copper, and
coal-tar solvent naphtha will give a varnish which, when suitably
thinned and the coats stoved at a heat below 212 deg. F., will give a
green japan second to none as a finishing coat as regards purity of
tone at least. To harden it and render it more elastic half of the
rosin might be replaced by equal weights of a copal soluble in solvent
naphtha and boiled linseed oil, so that the mixture would stand thus:
rosinate of copper 1 lb., rosin 1/2 lb., boiled oil 1/4 lb., hard
resin (copal) 1/4 lb., solvent naphtha 1 lb. When heated to a high
temperature this rosinate of copper varnish yields a magnificent ruby
bronze coloration, especially on glass. Verdigris dissolves in
turpentine, and successful attempts might be made to make a green
japan varnish from it on the lines indicated for rosinate of copper.
ORANGE-COLOURED GROUNDS.
Orange-coloured grounds may be formed by mixing vermilion or red lead
with King's yellow, or orange lake or red orpiment (? realgar) will
make a brighter orange ground than can be produced by any mixture.
PURPLE GROUNDS.
Purple grounds may be produced by the admixture of lake or vermilion
with Prussian blue. They may be treated as the other coloured grounds
as regards the varnish vehicle.
BLACK GROUNDS.
Black grounds may be formed either from lamp black or ivory black, but
ivory black is preferable to lamp black, and possibly carbon black or
gas black to either. These may be always applied with the shellac
varnish as a vehicle, and their upper or polishing coats may consist
of common seed-lac varnish. But the best quality of ivory black ground
in the best super black japan yields, after suitable stoving, a very
excellent black indeed, the purity of tone of which may be improved by
adding a little blue in the grinding.
COMMON BLACK JAPAN GROUNDS ON METAL.
Common black japan grounds on metal by means of heat are procured in
the following manner: The surface to be japanned must be coated over
with drying oil, and when it is moderately dry must be put into a
stove of such heat as will change the oil black without burning it.
The stove should not be too hot when the oil is put into it nor the
heat increased too fast, either which error would make it blister, but
the slower the heat is increased and the longe
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