CERTAIN IMPROVEMENTS IN THE PRODUCTION OF TYPOGRAPHICAL ETCHED PLATES REPRODUCING PHOTOGRAPHS FROM NATURE OR FROM COPY
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Edmond Capron, Leon Duvivier, and
Noel Ponsolle, junior, at the Office of the Commissioners of Patents on the 29th
October 1877.
EDMOND CAPRON, Photographer, LEON DUVIVIER, Agent for Insurance Company,
and NOEL PONSOLLE, junior, Agent for Insurance Company, all of Paris, 17,
Boulevard St. Martin, in the French Republic. "CERTAIN IMPROVEMENTS IN THE
PRODUCTION OF TYPOGRAPHICAL ETCHED PLATES REPRODUCING PHOTOGRAPHS FROM
NATURE OR FROM COPY."
This Invention relates to an improved process for obtaining typographic plates,
reproducing photographs from nature, or from copies, with their mezzotints.
In carrying out this Invention we proceed in the following manner:-
We prepare
by the application of a layer or coating of the composition herein-after described a
metal glass or ceramic plate, which, under the action of the light, receives the
impression of a photographic plate; the image thus obtained transferred to the
metal or other plate, as before mentioned, is submitted to the action of acids
according to one of the usual and well-known processes, and the plate is then ready
for printing.
The layer or coating herein-before referred to is composed of the following
ingredients or others possessing equivalent properties in about the under-mentioned
proportions, which may however be varied according to circumstances, and it is
prepared in the following manner:-We steep in a porcelain or other vessel
15 parts by weight of amber gelatine, 3 parts by weight of loaf sugar, and 125 parts
by weight of distilled water; and we introduce into another vessel composed
by preference, of glazed fireproof ware, 3 parts by weight of isinglass (first quality),
and 175 parts by weight of distilled water. These two solutions are allowed to
stand for, say, from 10 to 20 hours in an atmosphere of a temperature of, say,
about 3° centigrade, after which the isinglass is boiled (whilst being kept stirred) on
an open wood charcoal fire for, say, about 20 minutes, and placed aside, and the
gelatine is dissolved with a water bath at a temperature as low as possible. To the
gelatine solution is then added about 4 parts by weight of bichromate of potash,
the mixture being well stirred in order to accelerate the solution and prevent cooling.

page_text: The solution thus obtained is then added, whilst still stirring, to the, isinglass
solution in its vessel, and the whole is filtered through suitable flannel free from
traces of soap, care being taken to accelerate the filtration by pressing the flannel in
order to cause the thickest portion of the composition to pass. This operation is
performed over a glass having a spout or lip, and the mixture is then poured over
an unpolished plate of copper, zinc, or plate glass.
The plate employed should be slightly warmed before the mixture is applied, and
afterwards laid flat upon a marble in a stove maintained for about 3 hours at a
temperature of, say, about 40° centigrade, after which when cooled it may receive
an impression by the action of light behind a photographic plate.
The process is then continued as for ordinary printing with fatty ink upon
gelatine, employing transfer ink and transfer paper. The image obtained is then to
be transferred to a plate of zinc, for example, and bitten in.
The grain obtained by means of this process enables a plate to be produced,
suitable for typographic printing.
The place in which all the herein-before described operations are to be performed
must be maintained at a uniform temperature of, say, from about 25° to
30° centigrade.