IMPROVEMENTS IN THE PRODUCTION OF PLATES OR CASTS FOR TYPOGRAPHIC AND OTHER PURPOSES OF MEDALLIONS AND OTHER LIKE ARTICLES, AND OF OBJECTS GENERALLY HAVING DESIGNS, PATTERNS, OR DEVICES IN RELIEF
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office
of the Commissioners of Patents on the 15th June 1877.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. “IMPROVEMENTS IN THE PRODUCTION OF PLATES OR CASTS FOR
TYPOGRAPHIC AND OTHER PURPOSES OF MEDALLIONS AND OTHER LIKE ARTICLES,
AND OF OBJECTS GENERALLY HAVING DESIGNS, PATTERNS, OR DEVICES IN RELIEF."
A communication from abroad by Charles Gustave Rodrigues Percire, of Paris, in
the Republic of France.
This Invention relates to a new process for obtaining from photographic pilates of
any description, and from designs on glass made with varnishes or other suitablo
materials, stereotype, electro, metallurgical, or cast or moulded plates, articles of
jewellery, medallions, and work generally in bas-relief, demi-relief, or high-relief.
In carrying out this Invention it is proposed to proceed in the following manner:-
The first oporation consists in the preparation of gelatine plates of much greater
thickness than those hitherto used in what are known as the gelatine processes.
The gelatine is put in solution in water with a certain quantity of pounded indian
ink (say about from 1/2 to 3 per cent. in weight), and the two substances aro
intimately mixed together by agitation carried on for sufficient period in a vessel
heated with a water bath. A sheet of paper of suitable thickness, according to the
thickness of the layer of gelatine which it is to receive, is at the same time dipped
in warm water, the paper being supported on a glass plate; after remaining for a
sufficient period in the warin water, the glass plate and the sheet of paper which it
supports are withdrawn, drained, and placed on a table. The operator then takes
some thicknesses of dry paper and a printing roller and dabs the paper and spreads
it out carefully on the glass plate; after which he raises the edges of the sheet of
paper and runs thereunder the warm solution (which has been previously filtered)
of gelatine and indian ink, in the same manner as collodion is ordinarily applied
to glass plates. The paper with the solution applied is then dried by the whole
being placed horizontally in a stove heated to a low temperature.
When the gelatine plates thus run upon paper are required to be of a considerable
thickness, the sheets of paper are placed upon metal plates having rims or flanges
intended to support the raised edges of the said sheets of paper while the warm
011

page_text: solution of gelatine and indian ink is being run thereunder; and in order to
accelerate the operation of drying, vessels containing quicklime or chloride of
calcium may be placed in the drying stove.
Gelatine plates thus obtained on paper possess the following advantages:—
1. They dry very rapidly, the bichromate herein-after referred to not entering
into their preparation.
2nd. They are not susceptible of deterioration, the carbon of the indian ink acting
as an antiseptic.
3rd. They present a fine grained surface due to the infinitesimal particles intro-
duced by the addition of the indian ink.
Plates of gelatine upon paper thus prepared may be kept without inconvenience
for a number of days without being used.
In lieu of employing indian ink, various colors may be mixed with the gelatine
in order to facilitate the action of the light upon the gelatine, the color varying
according to circumstances and the result to be obtained.
When the plates of gelatine upon paper are about to be used, they are dipped
into a bath of bichromate, such, for example, as bichromate of potash, and then left
to dry; after which such plates with the plates or designs on glass superposed are
placed in suitable frames and exposed to the action of the light for the requisite
period. The photographic plates or designs on glass are then removed, and the
gelatine plate is turned round and applied carefully in order to fix it (after having
covered it with a thin coating of gumlac or collodion) to a glass plate in such a
manner that the paper shall be at the upper side. The paper is then saturated
with warm water and separated from the gelatine; after which the gelatine is
washed with warm water so as to dissolve and completely remove all the parts of
the gelatine which have not been hardened by the exposure to the light; and as
the parts which have been hardened by such exposure to the light adhere firmly to
the glass, there remains, after the operation of washing, a surface in relief which
retains, by reason of the small number of manipulations to which it has been
subjected, all the sharpness and mezzotints of the original, and the profiles of which
correspond in a bevel form with the glass plate. The gelatine plate thus prepared
and treated is then allowed to dry, aftor which the surface in relief receives a thin
conting of india-rubber varnish: Plaster casts are then taken, from which may be
obtained, by known processes and with any suitable materials, stereotype, electro,
metallurgical, or cast or moulded plates, also articles of jewellery, medallions, and
work generally in bas-relief, demi-relief, or high-relief.