IM- PROVEMENTS IN THE PRODUCTION OF PHOTOGRAPHIC RELIEF PLATES OR 'PHOTO- ELECTROTYPES' FOR PRINTING
Year: 1877

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake, & Co.,
Patent Agents, Southampton Buildings, London, for the Invention of "IM-
PROVEMENTS IN THE PRODUCTION OF PHOTOGRAPHIC RELIEF PLATES OR 'PHOTO-
ELECTROTYPES' FOR PRINTING." A communication from abroad by William
Howard Mumler, of Boston, Massachusetts, United States of America, Photo-
Orapher
Sealed the 13th July 1877, and dated the 7th May 1877.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 7th May 1877.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN THE PRODUCTION OF PHOTO-
GRAPHIC RELIEF PLATES OR PHOTO-ELECTROTYPES' FOR PRINTING." A communi-
cation from abroad by William Howard Mumler, of Boston, Massachusetts, United
States of America, Photographer.
Many experiments have been made with regard to the re-production of engravings
and other prints by means of a printing press without the trouble and expense of
re-engraving the subject, and several Inventions have been worked more or less
successfully, all of which are founded upon the discoveries of Mungo Ponton, an
English chemist, in 1839, and M. Poitevin, a French engineer, in 1855, namely, that
bichromatized gelatine when acted upon by light becomes insoluble in water, and
possesses the properties of lithographic stone, and may be used as such.
In photo-lithography and photo-zincography a transfer is made on stone or zinc
by means of gelatine, and the printing is done from the surface of the stone or
zinc by means of lithographic ink and a press.
In photo-galvanography the gelatine film or plate after having the picture printed
thereon, and the parts not acted upon by the light swollen by water, is made to
serve as the basis of electrotyping.
In the Woodbury type process a sheet of gelatine, from which the parts not acted
upon by light have been washed away, is used as the means for obtaining by
hydraulic pressure a metal mould; this mould is filled for every impression with

page_text: gelatine containing coloring matter, and the print is really an embossing of colored
gelatine on the sheet of paper.
In photo-collographic printing, or. the heliotype process, the printing is effected
directly from the flat level surface of the sheet of gelatine in the same manner that
lithographs are printed from stone, the superfluous chemicals contained in those
parts not previously acted upon by the light having been washed out without
washing away the gelatine.
My improved process differs froin all of these processes, and will be best under-
stood by a description of the various operations in detail, which go to make up the
complete process, which is as follows:-In the preparation of the gelatine plate I
use the following ingredients in about the proportions named below, namely,
gelatine, one ounce; fresh water, seven ounces; glycerine, two drams; saturated
solution of bichromate of potash, two drams. These ingredients are placed in a
vessel and subjected to a gentle heat, and when thoroughly dissolved and mixed
the mass is poured upon a smooth level metal or glass plate provided with ledges
raised about one-fourth of an inch above its upper surface around its outer edge,
until the fluid mass is even with the tops of said ledges, the surface of said plate
having been previously prepared by rubbing it with tallow to prevent the gelatine
from adhering thereto. The plate with the gelatine thereon is then put away in a
dark room to dry. When thoroughly dry the gelatine film is removed from the
glass or metal plate, and placed under a photagraphic negative, and exposed to the
light under the direct rays of the sun a sufficient time to print thereon a picture
from the negative in contact therewith. It is then removed from under the
negative, and secured to a base of glass, metal, or other suitable material, with the
face or printed side uppermost, by means of liquid glue or any other suitable
adhesive material that can be used in a cold state. The upper surface is then made
level and true by grinding the surface with emery paper or cloth, or other suitable
abrading material attached to a block of wood or other suitable material having a
true and level surface.
To prevent scratching by the emery or other abrading material, I rub the surface
with tallow until all the interstices are filled. The plate of gelatine with the
picture printed thereon is then treated with acetic acid by pouring it upon its upper
surface, and brushing such surface with a soft bristle brush to assist the acid in
dissolving the gelatine not acted upon by the light. Those parts acted upon by the
light being rendered insoluble thereby are unaffected by the acid, and as a con-
sequence are left in relief by the gradual dissolving or eating away of those parts
not acted upon by the light. When a sufficient depth has been obtained, or when
the acid has dissolved or eaten away the gelatine as deep as the light has penetrated,
the acid must be immediately washed off with water at about blood-heat. If any
trace of acid should remain it may be neutralized by exposing the plate to the
fumes of ammonia
If sufficient depth has not been obtained by this one treatment the interstices or
parts eaten away by the acid may be filled or coated with a paste composed of
mucilage or other suitable gum and bone black; or said parts may be coated with
indian ink, black shellac varnish, or any opaque or semi-transparent substance which
will prevent the passage of the actinic rays of light through the same, and that
may be readily removed again without injury to the gelatine plate.
Up to this time in my process all the operations upon the gelatine plate, except
while under the negative, must be performed in a dark room or in an anti-actinic
light. The plate covered or partially covered with the bone-black paste or other
protective coating, may now be exposed to the actinic light without the negative,
the paste or other coating preventing the action of the light, except upon the
lines left standing by the acid, and which are not covered by the paste.
This exposure may continue until the raised. lines become very hard; the plate is
then taken into the dark room again, where the paste or other coating is removed
by a suitable solvent. When this has been done the plate is again treated with
acetic acid as before. The plate may then be dried in the light until it becomes

page_text: hard in all its parts; it is then ready to electrotype in the same manner as a
woodcut is electrotyped.
It is well known that the face surface of type, woodcuts, and other plates from
which printing is to be done, must be true or level, in order that good work may
be produced therefrom; but this result has never been fully or satisfactorily
accomplished in any of the processes of producing prints by means of gelatine
plates.
Another difficulty heretofore encountered in trying to produce gelatine relief
plates has been that the outer edges of the lines left standing in relief, after treating
the plate with a solvent, turn or curve upward, and thereby destroy the even level
surface thereof, the effect being to make the lines when printed rough and
imperfect.
To obviate these difficulties, and give to the gelatine plates a true, straight, and
even surface, and prevent the turning up of the edges of the lines, I grind the face
surface of the gelatine plate after the picture has been printed thereon, and after
the gelatine film has been permanently secured to its base, as previously
described.
Another great difficulty heretofore met with has been occasioned by the use of
hot water as a solvent for the parts unaffected by the action of light in printing
the picture on the gelatine plate, which has heretofore been the practice.
To obviate this difficulty I use acetic acid in a cold state as a solvent, which
affects the gelatine plate only so far as it has not been acted upon by actinic light,
acetic acid having no effect upon bichromatized gelatine that has been exposed to
the action of actinic light when said acid is used in a cold state; but in the same
cold state said acid is a very ready solvent of gelatine, however hard, if it has not
been exposed to the action of actinic light.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 2nd
November 1877.
་
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN THE PRODUCTION OF PHOTO-
GRAPHIC RELIEF PLATES OR PHOTO-ELECTROTYPES FOR PRINTING." A communi-
cation from abroad by William Howard Mumler, of Boston, Massachusetts, United
States of America, Photographer.
Many experiments have been made with a view to the re-production of engravings
and other prints by means of a printing press without the trouble and expense of
re-engraving the subject, and several Inventions have been worked more or less
successfully; all of these are founded upon the discoveries of Mungo Ponton, an
English chemist, A.D. 1839, and M. Poitevin, a French engineer, A.D. 1855, namely,
that bichromatized gelatine when acted upon by light becomes insoluble in water,
and possesses the properties of lithographic stone, and may be used as such.
In order to more clearly set forth the distinguishing features of this Invention,
and the difference between the same, and the various processes heretofore employed,
I will give a short summary of the main features of the more prominent of these
processes now in use.
In photo-lithography and photo-zincography a transfer is made on stone or zinc
by means of gelatine, and the printing is done from the surface of the stone or
zinc by means of lithographic ink and a press.
In photo-galvanography the gelatine film or plate after having the picture printed
thereon, and the parts not acted upon by the light swollen by water, is made to
serve as the basis of electrotyping.
In the Woodbury type process a sheet of gelatine, from which the parts not acted

page_text: upon by light have been washed away, is used as the means for obtaining by
hydraulic pressure a metal mould; this mould is filled for every impression with
gelatine containing coloring matter, and the print is really an embossing of colored
gelatine on the sheet of paper.
In photo-collographic printing, or the heliotype process, the printing is effected
directly from the flat level surface of the sheet of gelatine in the same manner that
lithographs are printed from stone, the superfluous chemicals contained in those
parts not previously acted upon by the light having been washed out without
washing away the gelatine.
My improved process differs from all these processes, and will be best understood
by a description of the various operations in detail which go to make up the com-
plete process as follows:-In the preparation of the gelatine plate I use the following
ingredients in about the proportions stated, namely, gelatine, once ounce; fresh
water, seven ounces; glycerine, two drams; saturated solution of bichromate of
potash, two drams. These ingredients are placed in a vessel and subjected to a
gentle heat, and when thoroughly dissolved and mixed the mass is poured upon a
smooth level metal or glass plate provided with ledges raised about one-fourth of
an inch above its upper surface around its outer edge until the fluid mass is even
with the tops of said ledges, the surface of said plate having been previously pre-
pared by rubbing it with tallow to prevent the gelatine from adhering thereto.
The plate with the gelatine thereon is then put away in a dark room to dry.
When thoroughly dry the gelatine film is removed from the glass or metal plate,
and placed under a photographic negative, and exposed to the light under the
direct rays of the sun a sufficient length of time to print thereon a picture from
the negative in contact therewith; it is then removed from under the negative, and
secured to a base of glass, metal, or other suitable material, with the face or printed
side uppermost, by means of liquid glue, or any other suitable adhesive material
that can be used in a cold state. The upper surface is then made level and true by
grinding the surface with emery paper or cloth, or other suitable abrading material
attached to a block of wood or other suitable material having a true and level
surface.
To prevent scratching by the emery or other abrading material, I rub the surface
with tallow until all the interstices are filled. The plate of gelatine with the
picture printed thereon is then treated with acetic acid by pouring it upon its upper
surface, and brushing such surface with a soft bristle brush to assist the acid in
dissolving the gelatine not acted upon by the light. Those parts acted upon by the
light being rendered insoluble thereby are unaffected by the acid, and as a con-
sequence are left in relief by the gradual dissolving or eating away of those parts
not acted upon by the light. When a sufficient depth has been obtained, or when
the acid has dissolved or eaten away the gelatine as deep as the light has penetrated
(which effect is indicated by a slight curving or crooking of the straight lines),
the acid must be immediately washed off with water at about blood-heat. If any
trace of acid should remain it may be neutralized by exposing the plate to the
fumes of ammonia.
If sufficient depth has not been obtained by this one treatment the interstices or
parts eaten away by the acid may be filled or coated with a paste composed of
mucilage or other suitable gum and bone black; or these parts may be coated with
india ink, black shellac varnish, or any opaque or semi-transparent substance which
will prevent the passage of the actinic rays of light through the same, and that
may be readily removed again without injury to the gelatine plate.
Up to this time in my process all the operations upon the gelatine plate, except
while under the negative, must be performed in a dark room or in an anti-actinic
light. The plate covered or partially covered with the bone-black paste or other
protective coating, may now be exposed to the actinic light without the negative,
the paste or other coating preventing the action of the light, except upon the lines
left standing by the acid, and which are not covered by the paste.
This exposure may continue for an indefinite time, or until the raised lines

page_text: become very hard, and the light has penetrated and acted upon the gelatine to a
sufficient depth; the plate is then taken into the dark room again, where the paste
or other coating is removed by a suitable solvent; for instance, if the paste of
mucilage and bone black be used cold water will serve as the solvent, and if a
varnish be used to hold the coloring matter, to render the coating opaque, alcohol
should be used as the solvent. When this has been done the paste is again treated
with acetic acid as before. The plate may then be dried in the light until it
becomes hard in all its parts; it is then ready to electrotype in the same manner
as a woodcut is electrotyped.
It is well known that the face surface of type, woodcuts, and other plates with
which printing is to be done, must be true, straight, or level, in order that good
work may be produced therefrom; but this result has never been fully or satis-
factorily accomplished in any of the processes of producing prints by means of
gelatine plates, for the reason that in removing the gelatine from the original
surface on which it was dried, and fastening the same to its base, it is very difficult
to preserve the level surface; and, morcover, the gelatine film when dry is not sure
to be of an even thickness, its upper surface sometimes being very irregular and
uneven.
Another difficulty heretofore encountered in experiments for the production
of gelatine relief plates has been that the outer edges of the lines left standing in
relief, after treating the plate with a solvent, turn or curve upward, and thereby
destroy the even level surface thereof, the effect of which is to make the lines when
printed rough and imperfect.
This difficulty is evidently occasioned by the partially insoluble nature of the
outer crust or coating of the gelatine film, which, in all the heretofore known pro-
cesses, is preserved intact. This outer crust is partially insoluble, and of a more
contractile nature than the other portions of the plate.
To obviate these difficulties, and give to the gelatine plate a true, straight, and
even surface, and prevent the turning up of the edges of the lines, I grind the
face surface of the gelatine plate after the picture has been printed thereon, and
after the gelatine film has been permanently secured to its base, as previously
described.
Another great difficulty heretofore met with has been occasioned by the use of
hot water as a solvent for the parts unaffected by the action of light in printing
the picture on the gelatine plate, which has heretofore been the practice.
Gelatine has a great affinity for hot water, and is easily dissolved therein; and,
in using it to cut away the parts of the plate not acted upon by the light, the heat
from the water penetrates the entire plate, and partially dissolves or softens the
whole plate, and throws the lines out of shape.
To obviate this difficulty I use acetic acid in a cold state as a solvent; this acid
affects the gelatine plate only so far as it has not been acted upon by actinic light,
acetic acid having no effect upon bichromatized gelatine that has been exposed to
the action of actinic light when said acid is used in a cold state; but in the same
cold state the said acid is a very ready solvent of gelatine, however hard, if it has
not been exposed to the action of actinic light, therefore the lines, however fine, are
preserved intact, and kept from being thrown out of shape.
Having thus fully described the said Invention as communicated to me by
my foreign correspondent, and the manner of performing the same, I wish it
understood that I claim,-
First. The process, herein described, of obtaining level, straight, and true surfaces
on gelatinous films, from which to produce relief plates for printing, by grinding
the surface of the said film with emery cloth, or other suitable abrading material,
properly extended upon and secured to a true flat surface of wood or other suitable
material, as above described.
Second. The process of producing relief surfaces upon gelatine plates by photo-
graphing or printing from a photographic negative, the picture to be re-produced
upon the surface of the said gelatine plate, grinding the surface of the plate either

page_text: before or after printing thereon the picture, and then treating it with acetic acid in
the manner herein set forth.
"
or
Third. The process, herein described, of producing gelatine relief plates by photo-
graphing or printing from a photographic "negative positive" upon the
surface of the gelatine plate, the picture to be produced in relief, treating the plate
with acetic acid until it has eaten away the gelatine to as great a depth as possible
without injury to the lines, removing the acid and coating or filling the parts acted
upon by the acid with a paste made of bone black and any suitable gum, or with
indian ink, black shellac varnish, or other opaque or semi-transparent substance,
then exposing the plate to the direct rays of light without the negative or positive
plate, and, after removing the paste or other opaque or semi-transparent substance,
treating the gelatine plate with acetic acid a second time, as above described.
Fourth. In the process of producing gelatine relief plates, treating the plate
after a partial relief has been produced, with a coating of bone-black paste, indian
ink, black shellac varnish, or other opaque or semi-transparent substance, in the
manner herein described, for the purpose specified.
Fifth. The method of preventing the scratching of the surface of the gelatine
plate by the emery or other abrading material, by filling the interstices of the
abrading surface with tallow or equivalent material, as above described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Second day of November, in the year of our Lord One
thousand eight hundred and seventy-seven.