The Artist's Assistant, In the Study and Practice of Mechanical Sciences: Calculated for the Improvement of Genius. Illustrated with Copper-Plates (Birmingham, [ca. 1785])

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THE ARTIST'S ASSISTANT. 161

under coat is, that it makes a faving in the quantity
of varnifh ufed ; becaufe the matter of which the
riming is compofed fills up the inequalities of the
bodv to be varnifhed. and makes it eafy, by means of
rubbing and water-polifhmg, to gain an even furface
for the varnifh. This was therefore fuch a conveni-
ence in the cafe of wood, as the giving a hardnefs
and firmnefs to the ground was alfo in the cafe of
leather, that it became an eftablifhed method ; and
is therefore retained, even in the inftance of the
papier mache, bv the French, who applied the
received method of japanning to that kind of work
on its introduction. There is, neverthelefs, this in-
convenience always attending the ufe of an under
scat of fize, that the japan coats of varnifh and co-
lour will be conftantly liable to be cracked and
peeled off, by any violence, and will not endure
near fo long as the bodies japanned in the fame
manner, but without any fuch priming. This may
be eafily obferved in comparing the wear of the
Paris and Birmingham fnuff-boxes ; which latter,
when good of their kind, never peel or crack, or
fuffer any damage, unlefs by great violence, and
fuch a continued rubbing, as waftes away the fub-
ftance of the varnifh ; while the japan coats of
the Parifian boxes crack and fly off in flakes, when-
ever any knock or fall, particularly near the
edges, expofes them to be injured. But the Bir-
mingham manufacturers, who originally praftifed the
japanning only on metals, to which the reafon
above given for the ufe of priming did not extend,
and who took up this art of themfelves as an in-
vention, of courfe omitted at firft the ufe of any
fuch under coat; and not finding it more neceffaty

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