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-mâché 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