IMPROVEMENTS IN PRODUCING COPPER AND OTHER PLATES FOR PRINTING
Year: 1854

page_text: LETTERS PATENT to Paul Pretsch, of Sydenham, in the County of Surrey,
Photographer, for the Invention of "IMPROVEMENTS IN PRODUCING COPPER
AND OTHER PLATES FOR PRINTING."
Scaled the 4th May 1855, and dated the 9th November 1854.
PROVISIONAL SPECIFICATION left by the said Paul Pretsch at the
Office of the Commissioners of Patents, with his Petition, on the
9th November 1854.
I, PAUL PRETSCH, of Sydenham, in the County of Surrey, Photographer,
do hereby declare the nature of the said Invention .for "IMPROVEMENTS IN
PRODUCING COPPER AND OTHER PLATES FOR PRINTING," to be as follows:-
My said Invention consists in adapting the photographic process to the
purpose of obtaining a raised surface on glass or other suitable materials,
covered with gelatinous substances mixed with known photographic materials,
which can then be copied by the electrotype process, or by other means, for
producing moulds or plates suitable for printing purposes.
The coated glass or other plates which I employ, when taken from the photo-
graphic apparatus or copying frame,. have flat surfaces, and therefore must be
treated with solutions containing alcohol, water, borax, and other like suitable
chemical ingredients, by which means certain parts of the photographic copy
will be removed and other parts remain raised, and is then ready to be made

page_text: firm, by applying astringents and drying varnish. The surfaces thus prepared
are next made conducting, and must be placed in the galvano-plastic apparatus
for obtaining a copper plate, or the same must be stereotyped or otherwise
copied; such plates will be similar to engraved plates, and be equally suitable
for printing. I sometimes reverse this process, by producing raised surfaces
to print from.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Paul Pretsch in the Great Seal Patent Office on the
8th May 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PAUL
PRETSCH, of Sydenham, in the County of Surrey, Photographer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of November, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for. Herself, Her heirs and successors, give and grant unto me,
the said Paul Pretsch, Her special licence that I, the said Paul Pretsch,
my executors, administrators, and assigns, or such others as I, the said
Paul Pretsch, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN PRODUCING COPPER AND OTHER PLATES FOR PRINTING," upon the condition
(amongst others) that I, the said Paul Pretsch, by an instrument in writing
under my hand and seal, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Paul Pretsch, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
My said Invention consists in adapting the photographic process to the
purpose of obtaining either a raised or a sunk design on glass or other suitable
material or materials, covered with glutinous substances mixed with photo-

page_text: graphic materials, which aforesaid design can then be copied by the electrotype
process, or by other means, for producing plates suitable for printing purposes,
or can be applied for producing moulds applicable for obtaining plates.
And for the better understanding of my said Invention, I will now proceed
to describe the details of the several processes by which the same may be
carried into operation.
I first prepare a solution of about two parts of clear glue in about ten
parts of distilled water, using more or less of either, as may be required;
and to one part of a strong solution of nitrate of silver, and one part of a
weak solution of iodide of potassium, each in a separate glass, I pour a
small quantity of the glue solution. The remainder of the glue solution
must be kept warm, and a very strong solution of bichromate of potass well
stirred up in it. I then add the prepared glutinous solutions of nitrate of
silver and, of iodide of potassium, and strain the mixture for use. I next
take a clean plate of glass, or silvered copper plate, or other suitable plate,
and placing it quite level; pour the above mixture over its surface, which
will form a coating thereon when completely dry. The print or other subject
to be copied being laid on the prepared coated surface, they are to be placed
together in a photographic copying frame, and exposed to the influence of
the light. After a sufficient exposure, the frame must be opened, the plate
removed, and washed either with cold water, or a solution of borax or of car-
bonate of soda, as may be necessary. The photographic picture or design will
be found to appear in relief, and when sufficiently developed must be washed
with spirits of wine. The surplus moisture is to be removed, and the plate
covered with a mixture of copal varnish diluted with oil of turpentine. After
some time, and before becoming quite dry, the superfluous varnish must be
removed with oil of turpentine, and the plate immersed in a very weak solution
of tannin, or other suitable astringent. During this part of the
process the
plate must be carefully watched, and removed as soon as the picture or design
is considered sufficiently raised; it is then washed in water and dried. In this
state the plate is ready to be copied. This may be effected by the customary
methods of rendering the coating conducting, and placing it in the electrotype
apparatus, or by making a mould from the coated plate, which, being subjected
to the electrotype process, will also afford the required printing plates; or
sometimes the copying may be done by the stereotype or other like process.
Or, secondly, I proceed by employing a solution of gelatine, prepared with
chemicals, as already described, with which I coat the plate, and operate for
copying the same, as first detailed; but after washing with spirits of wine the
plate must be dried, and in due time the picture or design will appear sunk,

page_text: like an engraved plate. The production of printing plates therefrom is to be
proceeded with, as before described.
Or a third process may be adopted by applying printing ink to the coating
of the plate, prepared as above described, taking the impression upon paper
laid thereon, which impression or print can be transferred to zinc or stone, and
printed by the usual methods.
Having thus fully described several modes of proceeding to carry out the
object of my said improvements, I would here remark that the coated glass,
metal, or other plates which I employ when taken from the photographic
apparatus or copying frame have flat surfaces, and therefore must be treated
with water, alcohol, or solutions of borax, and other like suitable chemical
ingredients, by which means certain parts of the photographic copy will appear
raised and others sunk, and is then ready to be made firm, if necessary, by
applying. astringents and drying varnish. The surfaces thus prepared, or the
moulds prepared from them, are next made conducting, and must be placed
in the galvano-plastic apparatus for obtaining a plate, or the same can be
stereotyped or otherwise copied. Instead of the. iodide of potassium, the
ammonium bromide or ammonium iodide may be employed, as they shorten
the time of exposure, and likewise the copy can then be obtained by the
photographic camera instead of the copying frame. As my 'Invention is
capable of being variously modified, I do not restrict myself to the precise
processes described, nor to any particular chemical ingredients or photographic
or galvanić apparatus, so long as the object of my improvements results from
employing the whole or any part of the same, or modifications thereof. And
I do declare that what I claim as my Invention is, namely, the peculiar
adaptation of the photographic process to the production of printing plates in
copper and other metals and materials, as described.
In witness whereof, I, the said Paul Pretsch, have hereunto set my hand
and seal, this Seventh day of May, in the year of our Lord 1855.