mixed together to form any compound colour, such as
blue and yellow to form green. The pigments used
for japan grounds should all be previously ground
very smooth in spirits of turpentine, so smooth that
the paste does not grate between the two thumb nails,
and then only are they mixed with the varnish.
This mixture of pigment and varnish vehicle should
then be spread over the surface to be japanned very
carefully and very evenly with a camel-hair brush.
As metals do not require a priming coat of size and
whiting, the japan ground may be applied to metallic
surfaces forthwith without any preliminary treatment
except thorough cleansing, except in the cases specially
referred to further on. On metallic surfaces three
to four coats are applied, and in the interval between
each coat the articles must be stoved in an oven heated
to from 250 deg. to 300 deg. F.
The formation of a perfectly white japan ground and
of the first degree of hardness has always been difficult
to attain in the art of japanning, as there are few
or no substances that can be so dissolved as to form
a very hard varnish coat without being so darkened
in the process as to quite degrade or spoil the whiteness
of the colour. The following process, however,
is said to give a composition which yields a very
near approach to a perfect white ground: Take
flake white or white lead washed and ground up with
the sixth of its weight of starch and then dried,
temper it properly for spreading with mastic varnish
made thus: Take 5 oz. of mastic in powder and
put it into a proper vessel with 1 lb. of spirits
of turpentine; let them boil at a gentle heat till
the mastic be dissolved, and, if there appear to be
any turbidity, strain off the solution through flannel.
Apply this intimate and homogeneous mixture on the
body to be japanned, the surface of which has been
suitably prepared either with or without the priming,
then varnish it over with five or six coats of the
following varnish: Provide any quantity of the
best seed-lac and pick out of it all the clearest
and whitest grains, take of this seed-lac 1/2 lb. and
of gum anime 3/4 lb., pulverize the mixture to a coarse
powder and dissolve in a gallon of methylated spirits
and strain off the clear varnish. The seed-lac
will give a slight tint to this varnish, but it cannot
be omitted where the japanned surface must be hard,
though where a softer surface will serve the purpose
the proportion of seed-lac may be diminished and a
little turpentine oleo-resin added to the gum anime
to take off the brittleness. A very good varnish
entirely free from brittleness may, it is said, be
formed by dissolving gum anime in old nut or poppy
oil, which must be made to boil gently when the gum
is put into it. After being diluted with turps
the white ground may be applied in this varnish, and
then a coat or two of the varnish itself may be applied
over it. These coats, however, take a long time
to dry, and, owing to its softer nature, this japanned
surface is more readily injured than that yielded by
the shellac varnish.
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