IMPROVEMENTS IN THE PREPARATION OF PRINTING SURFACES BY THE AID OF PHOTOGRAPHY
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Robert Henelade Courtenay at
the Office of the Commissioners of Patents, with his Petition, on the
26th November 1866.
I, ROBERT HENELADE COURTENAY, of No. 4, Meyrick Road, Clapham
Junction, in the County of Surrey, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE PREPARATION OF PRINTING SURFACES BY
THE AID OF PHOTOGRAPHY," to be as follows:-
The first part of my Invention has for its object the production by the aid
of photography of engraved metal plates, which.may be printed from in the
ordinary manner of printing with type, and is more especially applicable to the
copying either on the same or an enlarged or reduced scale of original
drawings. I first obtain on a photographic plate a negative image of the
drawing, or it may be a negative image of other objects or views, and when
the view is taken from nature I apply a ground glass plate to receive the
collodion coating, and from this plate I print on to a transfer paper prepared
with a solution of gelatine, sugar, albumen, bichromate of potash, or.ammonia,
or both in combination with a quantity of bichloride of mercury and hypo-
sulphite of soda, or the ordinary photo-litho transfer paper may be used, or
transfer paper such as is used by lithographers may be employed; when the
paper is dried I print it under the negative in the ordinary manner; after
printing I ink the design with a good transfer ink and sponge the print in the
usual way done by lithographers, after drying the print is ready to be trans-.

page_text: ferred to the metal plate to be engraved. I either employ a zinc plate, or if
the plate be of other metal I prepare the surface of the plate on to which the
design is to be transferred by giving to it a thin coating of zinc. I prefer to
employ a thin plate of copper soldered at the back to a thicker plate of zinc,
and coated on the face by electro-deposition with a thin film of zinc, the face
of the plate is clean and is then ready to receive the photographic design; this
is done in the ordinary manner employed by lithographers to transfer a design
to a plate or stone from transfer paper; the plate is now etched with nutgalls,
and the transfer ink is cleaned off the plate
a mixture of Venice turpentine,
spirits of turpentine, linseed oil, varnish, and a solution of gum arabic; the
plate is now inked up with a mineral ink composed of metallic oxides, using
by preference either copper or iron, Venice turpentine, wax, and other fatty
matters, the metallic oxides give body and color to the ink, or a mixture of a
solution of gutta percha and metallic oxides with fatty matters may be
employed. The plate is afterwards protected at the back with a varnish of
asphaltum and wax, a copper wire being previously soldered to one end of the
plate; the plate is now dipped into a weak acid solution to remove the thin
zinc coating that is not covered with the ink.
For engraving or etching in the plate I employ a solution of commercial
salammoniac of common salt, or sulphate of zinc or copper, or chloride of
zine or copper, or any common metallic or alkaline salt, or a weak solution of
acid may be employed, but I prefer to employ an alkaline solution. The
plate is immersed in the solution, and the wire connected to it is attached to
the positive pole of a battery of low intensity, if the plate be of copper a
suitable copper plate is attached to the negative pole of the battery, and this
is also the case if the plate be of zine, the copper plate being separated from
the zinc by a porous partition; when the fine work is sufficiently engraved the
plate is allowed to dry, and these parts are protected with an asphaltum
varnish; the plate is then again submitted to the action of a stronger battery
and is afterwards again allowed to dry, and portions of the design again
stopped out, and the plate is again subjected to the action of a still stronger
battery until the required depth for the broad lights is obtained; the plate is
nów cleaned from ink and varnish, and is then ready for printing from in the
ordinary manner of type printing. One of the advantages of this process is that
the work is not rotten, all the lines being perfectly V-shaped. Steel plates may
be engraved by this process by coating the surface of the steel when polished
with a thin film of copper and afterwards with a thin film of zinc. Rollers
may also be engraved in a similar manner to that described for engraving
plates.

page_text: For producing intaglio plates such as are used in the copper plate press I
proceed as follows:-I obtain a photographic picture on litho transfer paper
as before, and transfer it to the surface of a highly polished copper plate
coated with a thin film of zine; the plates are then etched and rolled up
with the mineral ink, as in the process above described, with the difference
that the bolder parts of the design in the foreground are built up a little
thicker with the mineral ink mixed with a little gum arabic and applied with
a sponge by rubbing with a circular motion, or retouching with the same ink
or asphaltum varnish with a fine sable pencil; the parts of the plate are
then submitted to the action of acidulated water to remove the zinc where
the design is not; the plate is now allowed to dry, and the whole is treated
with plumbago or a mixture of white and gold bronze powder, and placed in
the ordinary copper solution used for electrotyping and attached to a small
Smee's battery, or any other will do, Smee's is the most regular in action; the
small battery will give a very fiue deposit of copper, and when the deposit is
sufficiently thick, about the thickness of a thin card, the plate should be
attached to a battery of much greater power to obtain the required thickness,
or another plate may be soldered to the back of the electrotype. The plate
that originally held the design is removed, and the design will be found to be
engraved the exact depth of the thickness of the ink used to form the design.
By this process entaglio plates can be multiplied larger or smaller, or the
same size as the original with very little expense compared with the price of
engraving by hand.