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Page 7
VARNISHING JAPAN WORK.
Varnishing is the last and the finishing process in japanning. It
consists in (1) applying, and (2) polishing the outer coats of
varnish, which are equally necessary whether the plain japan ground be
painted on or not. This is best done in a general way with common
seed-lac varnish, except on those occasions where other methods have
been shown to be more expedient, and the same reasons, which decide as
to the propriety of using the different varnishes as regards the
colours of the ground, hold equally with those of the painting, for
where brightness is a material point and a tinge of yellow would
injure it, seed-lac must give way to the whiter resins; but where
hardness and tenacity are essential it must be adhered to, and where
both are necessary a mixed varnish must be used. This mixed varnish
should be made from the picked seed-lac as directed in the case of the
white japan grounds. The common seed-lac varnish may be made thus:
Take 1-1/2 lb. of seed-lac and wash it well in several waters, then
dry it and powder it coarsely and put it with a gallon of methylated
spirits into a Bohemian glass flask so that it be not more than
two-thirds full. Shake the mixture well together and place the flask
in a gentle heat till the seed-lac appears to be dissolved, the
shaking being in the meantime repeated as often as may be convenient;
then pour off all the clear and strain the remainder through a coarse
cloth. The varnish so prepared must be kept for use in a well-corked
glass vessel. The whiter seed-lac varnishes are used in the same
manner as the common, except as regards the substances used in
polishing, which, where a pure white or the greater clearness or
purity of other pigments is in question, should be itself white, while
the browner sorts of polishing dust, as being cheaper and doing their
business with greater dispatch, may be used in other cases. The pieces
of work to be varnished should be placed near the fire or in a warm
room and made perfectly dry, and then the varnish may be applied with
a flat camel-hair brush made for the purpose. This must be done very
rapidly, but with great care; the same place should not be passed
twice over in laying on one coat if it can possibly be avoided. The
best way of proceeding is to begin in the middle and pass the brush to
one end, then with another stroke from the middle pass it to the other
end, taking care that before each stroke the brush be well supplied
with varnish; when one coat is dry another must be laid over it in
like manner, and this must be continued five or six times. If on trial
there be not a sufficient thickness of varnish to bear the polish
without laying bare the painting or ground colour underneath more
varnish must be applied. When a sufficient number of coats of varnish
is so applied the work is fit to be polished, which must be done in
common work by rubbing it with a piece of cloth or felt dipped in
tripoli or finely ground pumice-stone. But towards the end of the
rubbing a little oil of any kind must be used with the powder, and
when the work appears sufficiently bright and glossy it should be
well rubbed with the oil alone to clean it from the powder and to give
it a still greater lustre. In the case of white grounds, instead of
the tripoli, fine putty or whiting should be used, but they should be
washed over to prevent the danger of damaging the work from any sand
or any other gritty matter that may happen to be mixed with them. It
greatly improves all kinds of japan work to harden the varnish by
means of heat, which, in every degree that can be applied short of
what would burn or calcine the matter, tends to give it a firm and
strong texture where metals form the body; therefore a very hot stove
may be used, and the stoving may be continued for a considerable time,
especially if the heat be gradually increased. But where wood or
papier-m�ch� is in question, heat must be applied with great caution.
SECTION III.
JAPANNING OR ENAMELLING METALS.
In japanning metals, all good work of which should be stoved, they
have to be first thoroughly cleaned, and then the japan ground applied
with a badger or camel-hair brush or other means, very carefully and
evenly. Metals usually require from three to five coats, and between
each application must be dried in an oven heated from 250� to 300�
F.--about 270� being the average. It has already been seen that the
best grounds for japanning are formed of shellac varnish, the
necessary pigments for colouring being added thereto, being mixed with
the shellac varnish after they have been ground into a high degree of
smoothness and fineness in spirits of turpentine. In japanning it is
best to have the oven at rather a lower temperature, increasing the
heat after the work has been placed in the oven. When a sufficient
number of coats have been laid on--which will usually be two only--the
work must be polished by means of a piece of cloth or felt dipped in
tripoli or finely powdered pumice-stone. For white grounds fine putty
powder or whiting must be employed, a final coat being afterwards
given, and the work stoved again. The last coat of all is one of
varnish. And here, as a preliminary remark, it is advisable that all
enamels and japans should be purchased ready-made, as any attempt to
make such is almost sure to end in disaster, while, owing to the fact
that such are only required for small jobs; it would involve too much
trouble and would not pay. It is for this reason that few japan
recipes are given, as, although many are available, they do not always
turn out as suitable for the purpose as could be desired, in addition
to which the ready-made articles can be purchased at a very reasonable
price and are much better prepared. The operator should procure his
enamels a shade or two lighter than he desires to see in the finished
article, allowing the chemical action due to the stoving to tone the
colours down. Another necessity is to keep the enamel thoroughly well
mixed by well stirring it every time it is used, as if this is not
done the actual colouring matter is apt to sink to the bottom, the
ultimate result being that streaky work is produced in consequence of
this indifferent mixing of the enamelling materials.
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