ENAMELLED, PATENT, OR JAPANNED LEATHER.
These are terms used to designate those leathers, whether of the ox,
the horse, the calf, or the seal, which are finished with a waterproof
and bright varnished surface, similar to the lacquered wood-work of
the Japanese. The name "enamelled" is generally applied when the
leathers are finished with a roughened or grained surface, and "patent"
or "japanned" are the terms used when the finish is smooth. Though
generally black, yet a small quantity of this leather is made in a
variety of colours.
In America, large thin hides are principally used for the purpose.
They are limed and bated in the usual way, stoned after bating, and
tanned with hemlock and oak barks in a paddle tumbler, which is run for
10-15 minutes in each hour. When one-third tanned, they are levelled
on the flesh, and split with the belt-knife splitter, Fig. 52. After
splitting, the portions are drummed with strong gambier liquor for 1/4
hour, and then tanned out with bark. The grains are scoured with the
Fitzhenry or Lockwood machine (Figs. 53 and 56). They are then lightly
oiled and stretched on frames which can be enlarged by screws or a sort
of knuckle-joint at the corners. When quite dry, they are grounded with
a mixture of linseed-oil with white lead and litharge, boiled together
and thickened with chalk and ochre. This is dried in closets heated by
steam, into which the frames are slid face downwards, the heat being
gradually increased from 80° to 160° F. (27° to 71° C.). If it be
desired to employ a higher temperature, the leather is first saturated
with a solution of 2 oz. each of borax and alum in 1 gal. water, when
temperatures of 230°-250° F. (110°-120° C.) may be used. The remaining
treatment is much as above described, but a little turpentine is used
to make the paint work freely. The final varnish is composed of 20
parts spirit of turpentine, 20 linseed oil, 10 thick copal varnish,
and 1 of asphaltum or other colouring material. This must be mixed 2-3
weeks before use, and applied with a brush.
The splits are also often enamelled, and as a preparation receive a
dressing of linseed-oil boiled to a jelly and thinned with turpentine
or naphtha. This is applied with a stiff brush after the splits are
stretched on the frames and are still damp, so that it does not
penetrate the leather, but forms a sort of artificial grain.
Leather destined to be finished in this way requires to be curried
without the use of much dubbing, and to be well softened. The English
practice is to nail the skins thus prepared, and quite dry, on large
smooth boards, fitted to slide in and out of stoves maintained at a
temperature of 160°-170° F. (71°-77° C.), coating them repeatedly with
a sort of paint composed (for black) of linseed-oil, lamp-black, and
Prussian blue, well ground together. Each coating is allowed to dry in
the stoves, before the next is applied. The number of coatings varies
with the kind of skin under treatment, and the purpose for which it is
intended. The surface of every coat must be rubbed smooth with pumice;
finally, a finishing coat of oil-varnish is applied, and, like the
preceding coats, is dried in the stove. The exact degrees of dryness
and flexibility, the composition of the paint, and the thickness and
number of the coats, are nice points, difficult to describe in writing.
This branch of the leather industry, so far as it relates to
calf-skins, is carried on to a larger extent, and has been brought
to greater perfection in Germany and France than in England. In the
former countries, the heat of the sun is employed to dry some of the
coatings. The United States have also brought this style to a high
degree of excellence, especially in ox-hides. There, use is said to
be made of the oils and spirits obtained from petroleum, and without
doubt, French and German emigrant workmen have materially assisted in
attaining this high standard.
Leather finished in these styles is used for slippers, parts of shoes,
harness, ladies' waist-belts, hand-bags, &c., and has now maintained a
place among the varieties of leather for a long period of years.