AN IMPROVED PROCESS OF EN- GRAVING
Year: 1862

page_text: LETTERS PATENT to Paul Emile Placet, of Paris, Cité Gaillard, No. 5,
Civil Engineer, for the Invention of "AN IMPROVED PROCESS OF EN-
GRAVING."
Sealed the 24th April 1863, and dated the 27th October 1862.
PROVISIONAL SPECIFICATION left by the said Paul Emile Placet at the
Office of the Commissioners of Patents, with his Petition, on the 27th
October 1862.
I, PAUL EMILE PLACET, of Paris, Cité Gaillard, No. 5, Civil Engineer, do
hereby declare the nature of the said Invention for "AN IMPROVED PROCESS
OF ENGRAVING," to be as follows:-
I spread on a clean glass a pretty thick coat of Judea bitumen, which when
desiccated I expose under a stereo or other like plate (cliché) or surface,
carrying the design to be engraved in a frame to the action of light. On being:
removed from the frame, the impressioned surface is covered with a coating of
gelatine, and when dry the whole is plunged in a mixture of naphtha and
benzine. The liquid penetrating under the coating removes the soluble parts
in contact with the glass, and soon the pellicle of gelatine becomes detached,
taking with it the parts which remain insoluble. I transport the sheet of
gelatine with the design or figure upwards to a flat surface of glass or metal.
If the proof be examined it will be found that the non-dissolved bitumen,
which constitutes the design or figure will appear in relief, which will be
bigher the more deeply the light has penetrated. The reliefs are similar to

page_text: those produced upon a print by the lines in an engraved plate. Then to
obtain a plate engraved in intaglio, it is accomplished by taking the mould of
this surface in relief, and by having recourse to galvanoplasty or to the electro-
type process, metal plates similar to the mould are obtained, which can be
used as in copper-plate printing.
Instead of using Judea bitumen as above described, similar results will be
obtained by the employment of any vegetable or animal substance which
becomes insoluble under the action of luminous rays, such as resins, mixtures
of bichromate of potass, or other salts sensitive to light, and an organic matter,
such as gum, dextrine, and albumen; and instead of gelatine as above
described, any agglutinous body may be used, such as gum, collodion, caoutchouc,
varnish, provided that this body shall have no action upon the sensitive coating,
and the solvent.
In order to give greater consistency to the gelatine, a sheet of paper, then
textile fabric, a strip of wood or thin sheet of porcelain may be made to adhere
to it before being dried. When a photographic design or picture (cliché) is
used, the different tints will be represented by reliefs proportioned to their
intensity for the light solidifies the coating so much the more deeply as it meets
with less resistance in traversing the plate, therefore the plates obtained in
such case are similar to plates engraved by aqua tinta. The necessary grain
for inking the plates may be obtained by mixing with the sensitive substance
a fine powder of some inert body such as quartz. The mixture of bichromate
of potass yields such high reliefs that I obtain plates engraved in such relief
that they are fit for typographic printing. In fact the means described will
afford, according to requirement, all kinds of engraved surfaces which may be
required to take prints or impressions or to decorate fancy articles, such as
vases, cases, bijous, and the like.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Paul Emile Placet in the Great Seal Patent Office on
the 27th April 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PAUL
EMILE PLACET, of Paris, Cité Gaillard, No. 5, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of October, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,

page_text: the said Paul Emile Placet, Her special licence, that I, the said Paul Emile
Placet, my executors, administrators, and assigns, or such others as I, the
said Paul Emile Placet, 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
"AN IMPROVED PROCESS OF ENGRAVING," upon the condition (amongst others)
that I, the said Paul Emile Placet, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,
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 Emile Placet, 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 thereof, that is to say:-
I spread on a clean glass a pretty thick coat of Judea bitumen, which when
desiccated, I expose under a stereo or other like plate (cliché) or surface
carrying the design to be engraved, in a frame to the action of light. On being
removed from the frame, the impressioned surface is covered with a coating of
gelatine, and when dry, the whole is plunged in a mixture of naphtha and
benzine. The liquid penetrating under the coating removes the soluble parts
in contact with the glass, and soon the pellicle of gelatine becomes detached,
taking with it the parts which remain insoluble. I transport the sheet of
gelatine with the design or figure upwards to a flat surface of glass or metal.
If the proof be examined, it will be found that the non-dissolved bitumen,
which constitutes the design or figure will appear in relief, which will be
higher the more deeply the light has penetrated. The reliefs are similar to
those produced upon a print by the lines in an engraved plate. Then to
obtain a plate engraved in intaglio, it is accomplished by taking the mould of
this surface in relief, and by having recourse to galvanoplasty or to the electro-
type process, metal plates similar to the mould are obtained, which can be used
as in copper-plate printing.
Instead of using Judea bitumen, as above described, similar results will be
obtained by the employment of any vegetable or animal substance, which
becomes insoluble under the action of luminous rays, such as resins, mix-
tures of bichromate of potass or other salts sensitive to light, and an organic

page_text: matter, such as gum, dextrine, and albumen. And instead of gelatine as above
described, any agglutinous body may be used, such as gum, collodion, caout-
chouc, varnish, provided that this body shall have no action upon the sensitive
coating and the solvent.
In order to give greater consistency to the gelatine, a sheet of paper, thin
textile fabric, a strip of wood, or thin sheet of porcelain may be made to adhere
to it before being dried. When a photographic design or picture (cliché)
is used, the different tints will be represented by reliefs proportioned to their
intensity, for the light solidifies the coating, so much the more deeply as it
meets with less resistance in traversing the plate; therefore the plates
obtained in such case are similar to plates engraved by aqua tinta. The
necessary grain for inking the plates may be obtained by mixing with the
sensitive substance a fine powder of some inert body, such as quartz. The
mixture of bichromate of potass yields such high reliefs that I obtain plates
engraved in such relief that they are fit for typographic printing. In fact the
means described will afford, according to requirement, all kinds of engraved
surfaces which may be required to take prints or impressions, or to decorate
fancy articles, such as vases, cases, bijous, and the like.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim the improved
process of engraving herein-before described.
In witness whereof, I, the said Paul Emile Placet, have hereunto set
my hand and seal, this Ninth day of April, One thousand eight hundred
and sixty-three.
Witness,
CH. ARMENGAUD, J.,
Ing. Civil,
23, Boulevt. de Strasbourg,
à Paris.
P. EM. PLACET. (L.S.)