IMPROVEMENTS IN THE PREPARATION OF GELATINE AND ALBUMen PHOTOGRAPHIC PLATES FOR PRINTING FROM WITH LITHOGRAPHIC INKS
Year: 1874

page_text: LETTERS PATENT to Pierre Auguste Despaquis, of 38, Southampton
Buildings, Chancery Lane, London, Photographer, for the Inven-
tion of "IMPROVEMENTS IN THE PREPARATION OF GELATINE AND ALBUMen
PHOTOGRAPHIC PLATES FOR PRINTING FROM WITH LITHOGRAPHIC INKS."
Sealed the 13th May 1875, and dated the 17th November 1874.
PROVISIONAL SPECIFICATION left by the said Pierre Auguste
Despaquis at the Office of the Commissioners of Patents, with his
Petition, on the 17th November 1874.
.
I, PIERRE AUGUSTE DESPAQUIS, of 38, Southampton Buildings,
5 Chancery Lane, London, Photographer, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE PREPARATION OF GELATINE
AND ALBUMEN PHOTOGRAPHIC PLATES FOR PRINTING FROM WITH LITHOGRAPHIC
INKS," to be as follows:-
This Invention of improvements in the preparation of gelatine and
albumen photographic plates for printing from with lithographic inks
is based upon the following observation :-That a layer of bichromated

page_text: gelatime intended to furnish a plate for impressions with lithographic
inks however thin it is may be divided into three parts or thicknesses.
In operating after the Poitevin process (process called Albertype) the
sensitive layer is thus composed: - Firstly, of a layer of albumen and
bichromate run over the surface of the glass; secondly, of a layer of
gelatine, also bichromated, covering the albumen, and together forming
the total layer to be converted into the plate for the impressions. This
total layer may then be divided into three thicknesses, the first attached
to the glass. and composed of albumen, the second forming the exterior
layer of gelatine, and the third forming the intermediate part between
the layer of albumen and the exterior part of the layer of gelatine. . .
Up to the present time all those who have employed this process or
the analogous processes of Edwards, or others, have proceeded as
follows: The layer of albumen being placed on the glass is rendered
partly insoluble either by the cooking or drying at a temperature of 60
to 80 degrees centigrade. It is then rendered totally insoluble and
adherent to the glass by solarization through the glass. This result
arrived at the layer is then covered over with another layer of bi-
chromated gelatine. This second layer being dried the glàss plate thus
prepared is placed in the pressure frame under the negative to be printed,
the gelatine side in contact with the negative and exposed to the light.
After exposure the plate is immersed in cold water to free it from the
bichromate not acted upon, or otherwise to fix it. In this manner two
only of the three layers of the total have been rendered insoluble by the
light, the one forming the support and adherent to the glass and in-
soluble beforehand, the other forming the exterior of the gelatine and
solarized under the negative. But this solarization under the negative
of the exterior of the layer of gelatine has penetrated unequally
according to the transparencies of the negative, and has not traversed
entirely the intermediate thickness, which consequently remains hygro-
metric, and will absorb the water like the exterior parts of the layer
which have been preserved from solarization by the opacities of the
negative, and should take the water which repels the fatty inks, so that
after a very limited number of proofs the intermediate layer is found
saturated with water, it loses its adherence to the layer of albumen
forming its support, and is dragged off by the inking roller and the plate.
is destroyed.

page_text: The printer to avoid the rapid destruction of the plate dares not
sufficiently water it before the passage of the inking roller, and the ink
not being sufficiently repelled in the whites and half tints the proof loses
its contrasts. To obviate these inconveniences after the two exposures
above named are made a third exposure must be made through the glass
to let the light penetrate, and consequently render it insoluble and
make it lose its hygrometric condition in its intermediato thickness
until it meets with the solarization which has had its action under the
negative up to the strong half lights, so as to stop the water passing
behind the blacks and half tints (the gelatine will take sufficient water
between the tones of the image), so that the two solarizations form the
two links of a chain and do not come away from the glass without great
difficulty, allowing a much greater number of proofs to be taken off.
This solidity of the layer allows the plate to be wetted much more, the
proof does not lose its contrasts, and the whites remain pure. The
application of this action may be made in other ways.
Firstly. In suppressing the preliminary exposure of the layer of
albumen, or if necessary suppressing it altogether, and commencing to
solarize the exterior layor under the negative, and then solarizing by the
ordinary light from the back of the glass until the action of the light
meets the blacks and deep half tints of the first solarization. It will be
seen quite easily when the two solarizations meet each other, and con-
sequently the moment to stop the exposure to light when the proof
commences to fade away and to become of one tint.
Secondly. If the layer of albumen has been first of all rendered
insoluble either by cooking or solarization through the glass by
recovering this first thickness by a second in bichromated gelatine, but
very thin, and calculated so that the solarization through the negative
allows the light to penetrate to give the blacks and the deep half tints
up to the layer of albumen, so as to render them adherent, in place of
employing the ordinary means of damping with a sponge, a method
which necessitates the use of a dry dabber to remove the excess of
water, and above all that left in the depressions forming the blacks of
the image and which should take the ink, I employ as part of my
Invention a roller in porous stone or Passy brick, which is rendered
specially porous and spongy. With this damping roller the damping is
only done in the reliefs of the plate, that is to say, in the parts not

page_text: solarized, and which ought to take the water and repel the fatty ink
and consequently form the lights of the picture; in this way, the water
not running over the entire plate but depositing itself solely on the
parts in relief, and which are the only parts requiring it, it becomes
unnecessary to use the dry dabber, and there is no fear of taking away
the water from the parts which should be saturated, which causes
the ink to adhere to these parts and equalizes the half tints with
the blacks and stains the white. My Invention rests then on the
observation that to obtain a photographic plate upon gelatine for
printing with lithographic inks (process Poitevin, Albert, or any
analogous one) fit to give a great number of proofs, and to prevent the
half tones equalizing themselves with the blacks, and the whites from
staining the general solarization through the supporting layer (or even
when there is no supporting layer, as in the process Edwards, or
gelatinised metallic plate) ought to be carried on until it meets with
the blacks and deep half tones of the exterior solarization under the
negative, so as to avoid leaving between the two solarizations in the
total layers an intermediate thickness, which remaining hygrometric by
the want of solarization quickly imbibes water after the drawing off of
a very few proofs and leads to the tearing up of the plate.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Pierre Auguste Despaquis in the Great Seal
Patent Office on the 15th May 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PIERRE
AUGUSTE DESPAQUIS, of 38, Southampton Buildings, Chancery Lane,
London, Photographer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventeenth day of November, in the
year of our Lord One thousand eight hundred and seventy-four, in the
thirty-eighth year of Her reign, did, for Herself, Her heirs and succes-
sors, give and grant unto me, the said Pierre Augusto Despaquis, Her
special license that I, the said Pierre Auguste Desqaquis, my executors,
administrators, and assigns, or such others as I, the said Pierre Auguste
Despaquis, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times

page_text: 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 Inven-
tion for "IMPROVEMENTS IN THE PREPARATION OF GELATINE AND ALBUMEN
PHOTOGRAPHIC PLATES FOR PRINTING FROM WITH LITHOGRAPHIC INKS," upon the
condition (amongst others) that I, the said Pierre Auguste Despaquis,
my executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, 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 Pierre Auguste Despaquis, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :—
This Invention of improvements in the preparation of gelatine and
albumen photographic plates for printing from with lithographic inks
is based upon the following observation :-That a layer of bichromated
gelatine intended to furnish a plate for impressions with lithographic
inks however thin it is may be divided into three parts or thicknesses.
In operating after the Poitevin process (process called Albertype) the
sensitive layer is thus composed :-Firstly, of a layer of albumen and
bichromate run over the surface of the glass; secondly; of a layer of
gelatine, also bichromated, covering the albumen, and together forming
the total layer to be converted into the plate for the impressions. This
total layer may then be divided into three thicknesses, the first attached
to the glass and composed of albumen, the second forming the exterior
layer of gelatine, and the third forming the intermediate part between
the layer of albumen and the exterior part of the layer of gelatine.
Up to the present time all those who have employed this process, or
the analogous processes of Edwards or others, have proceeded as
follows: The layer of albumen being placed on the glass is rendered
partly insoluble either by the cooking or drying at a temperature of 60
to 80 degrees centigrade. It is then rendered totally insoluble and
adherent to the glass by solarization through the glass. This result
arrived at the layer is then covered over with another layer of bi-

page_text: chromated gelatine. This second layer being dried the glass plate thus
prepared is placed in the pressure frame under the negative to be
printed, the gelatine side in contact with the negative and exposed to
the light, after exposure the plate is immersed in cold water to free
it from the bichromate not acted upon, or otherwise to fix it. In this
manner two only of the three layers of the total have been rendered
insoluble by the light, the one forming the support and adherent to the
glass, and insoluble beforehand, the other forming the exterior of the
gelatine and solarized under the negative. But this solarization under
the negative of the exterior of the layer of gelatine has penetrated
unequally, according to the transparencies of the negative, and has not
traversed entirely the intermediate thickness, which consequently
remains hygrometric, and will absorb the water like the exterior parts
of the layers which have been preserved from solarization by the opacities
of the negative, and should take the water which repels the fatty inks, 1
so that after a very limited number of proofs the intermediate layer is
found saturated with water it loses its adherence to the layer of albumen
forming its support and is dragged off by the inking roller, and the plate
is destroyed.
The printer to avoid the rapid destruction of the plate dares not
sufficiently water it before the passage of the inking roller, and the ink
not being, sufficiently repelled in the whites and half tints the proof
loses its contrasts. To obviate these inconveniences after the two
exposures above named are made a third exposure must be made
through the glass to let the light penetrate, and consequently render it.
insoluble and make it lose its hygrometric condition in its intermediate
thickness until it meets with the solarization which lias had its action
under the negative up to the strong half light, so as to stop the water
passing behind the blacks and half tints (the gelatine will take sufficient
water between the tones of the image), so that the two solarizations form
the two links of a chain and do not come away from the glass without
great difficulty, allowing a much greater number of proofs to be taken
off. This solidity of the layer allows the plate to be wetted, much more
the proof does not lose its contrasts, and the whites remain pure. The
application of this action may be made in other ways.
Firstly. In suppresing the preliminary exposure of the layer of
albumen, or if necessary suppressing it altogether, and commencing to
solarize the exterior layer under the negative, and then solarizing by

page_text: the ordinary light from the back of the glass until the action of the
light meets the blacks and deep half tints of the first solarization. It
will be seen quite easily when the two solarizations meet each other,
and consequently the moment to stop the exposure to light when the
proof commences to fade away and to become of one tint.
Secondly. If the layer of albumen has been first of all rendered in-
soluble either by cooking or solarization through the glass by recovering
this first thickness by a second in bichromated gelatine, but very thin,
and calculated so that the solarization through the negative allows the
light to penetrate to give the blacks and the deep half tints up to the
layer of albumen, so as to render them adherent, in place of em-
ploying the ordinary means of damping with a sponge, a method which
necessitates the use of a dry dabber to remove the excess of water,.
and above all that left in the depressions forming the blacks of the
image, and which should take the ink, I employ as part of my In-
vention a roller in porous stone or Passy brick, which is rendered
specially porous and spongy. With this damping roller the damping
is only done in the reliefs of the plate, that is to say, in the parts not
solarized, and which ought to take the water and repel the fatty ink,
and consequently form the lights of the picture; in this way the water
not running over the entire plate but depositing itself solely on the
parts in relief, and which are the only parts requiring it, it becomes
unnecessary to use the dry dabber, and there is no fear of taking away
the water from the parts which should be saturated, which causes the
ink to adhere to these parts and equalizes the half tints with the blacks
and stains the white. My Invention rests then on the observation
that to obtain a photographic plate upon gelatine for printing with
lithographic inks (process Poitevin, Albert, or any analogous one) fit
to give a great number of proofs and to prevent the half tones
equalizing themselves with the blacks and the whites from staining the
general solarization through the supporting layer (or even when there
is no supporting layer, as in the process Edwards, or gelatinized
metallic gauze) ought to be carried on until it meets with the blacks
and deep half tones of the exterior solarization under the negative, so
as to avoid leaving between the two solarizations in the total layers
an intermediate thickness, which remaining hygrometric by the want of
solarization quickly imbibes water after the drawing off of a very few
proofs, and leads to the tearing up of the plate.

page_text: I also proceed as follows:-A layer of bichromated gelatine having
been exposed under a negative is wetted on the face, that is to say,
upon the image by any means, either by immersion in cold water for
some minutes if the layer of gelatine is supported by an impermeable
plate, either of glass, metal, or wood, or with a sponge, if the support &
of the layer is permeable, such as gauze or paper, etc., so as to lift up
at the surface only of the layer the bichromate which is in the shades
of the image, then the bichromate being lifted up in that part of the
layer the plate is inked, so as the better to see if the bichromate is
enough lifted up; it should be just to the depth of the penetration of
the blacks. This being done all the plate is left to be acted on in
mixing the water of the surface with a little glycerine, which main-
taining a certain humidity on that surface prevents the gelatine from
becoming insoluble in that part, whilst all the part in the bottom
becomes completely insoluble and gives consequently a plate fit to yield
a great number of proofs.
I also add that for preparing the gelatinised cloth for use ás a printing
plate with fatty inks the cloth must be of flax or hemp, but not cotton
or wool, from which the gelatine comes away too easily, whilst it
remains perfectly adherent to the flax or hemp cloth.
To prevent the threads of the cloth from swelling and causing in-
equalities of surface in the layer when at the time of inking the pellicle
of gelatine the threads are enveloped with bichromated albumen by
pouring a thick layer on the cloth whilst still adherent to the glass upon
which the gelatine, which it recovers, has been run.
The albumen bichromated and acted on by light being completely
impermeable does not allow the water to enter to the cloth, which does
not swell up and leave a plane surface as if the support had been a plate
of glass.
It is well understood that the gelatine run on the glass should be well
congealed before recovering it with the wet cloth, upon which shall
follow the albumen coats, so that the albumen well envelopes the threads
of the cloth.
For the taking off the proofs I prefer a cylinder press, either in wood
or metal, arranged as herein-after described.
The Figure 1 of the Drawing attached shows in elevation a cylinder
press, given as an example only. The Figure 2 is a plan of the same.
In the two Figures the same letters indicate the same parts.
2

page_text: This press is composed of a cloth a, either an ordinary one or a
metallic gauze bearing a pellicle of gelatine incorporated and solarized
on both sides, as is described in my Patent, so that the two solari-
zations meet in the deep half tints, or a thin sheet of metal, zinc,
copper, etc., on which has been glued a pellicle forming a plate, and
sufficiently supple to have the effect of a band, and even a pellicle
attached upon a band in steel. well smoothed and solid. These different
bands bearing one, two, three, four, or a greater or less number of proofs,
turn on two rollers b, c, of which the one bears the handle d, and of
which the other is brought to or set away, as desired, the first by the
aid of the regulating screw e, so as to stretch the cloth, which need not
always be of the same dimensions either in length or breadth. A third
roller is placed against this c, so as to produce the pressure of the
paper 9 against the cloth a carrying the plate or plates in gelatine; this.
cloth is wetted by the rollers h, of which the upper in spongy matter;
sponge, etc., serves as feeder, it passes then to be inked under the inking
rollers i in any number, the rollers h and i giving by their own weight
upon the cloth, which is supported on a table j, the pressure sufficient
for the damping and inking. On the roller f turns an-endless cloth k
in flax or zinc, on this latter may be counterdrawn; the impressions in
fatty inks obtained on the gelatine pellicle; whether thick or supple,
producing the effect mentioned above; this cloth k passes over a second
moveable roller r, which serves to stretch it more or less; m, little roller
in wood, upon which is rolled the paper band, which unrolls, drawn by the
two large rollers ƒ and c, against which it will be pressed to receive the
image in ink; it is necessary that the two ends of the cloths should be
united by sewing, not forming a thick seam, so as to pass between the
two cylinders without shock.

page_text: Secondly. The spongy and hard roller above described serving to
distribute the water only on the parts of the plate in relief which have
need to receive it to prevent the destruction or rapid equalization of the
plates, which also abbreviates considerably the work of printing, and
above all allows, conjointly with the improvements described in claim 1, 5
the employment of the presses with mechanical action.
Thirdly. The use of the cloth and the sheets of zinc, which allows the
employment of the press, above described and illustrated in the annexed
Drawing, and to print upon a continuous band of paper.
In witness whereof, I, the said Pierre Auguste Despaquis, have 1
hereunto set my hand and seal, this Eighth day of May, in the
year of our Lord One thousand eight hundred and seventy-
five.
Witnesses,
D. H. BRANDON,
R. H. BRANDON,
PIERRE AUGUSTE DESPAQUIS. (L.S.)
13, Rue Gaillon,
Paris.