Year: 1888

page_text: Date of Application, 19th Jan., 1888
Complete Specification Left, 12th Oct, 1888
Complete Specification Accepted, 16th Nov., 188
I, ERNEST HOWARD FARMER of the Polytechnic School of Photography, 309 Regent
Street in the County of Middlesex, Photographer do hereby declare the nature of this
invention to be as follows: :―
I have discovered that an ordinary sensitive gelatino-bromide (or similar) plate can
after exposure be developed in such a way as to produce on its surface, degrees of
adhesiveness or absorptiveness in proportion to the varying intensities of light; and
that it will then give immediately, by ordinary printing methods, prints in either
aqueous or greasy pigments.
Although a result can be obtained on an ordinary gelatine plate, it is better to
specially prepare the plates.
For collotype or chromographic printing, glycerine or albumen or other soluble
coilloidal substance (such substances are carefully avoided in ordinary process) is added
to the other ingredients (gelatine and silver salt) in preparing the films and then with
the precaution mentioned below it is found that development gives varying degrees of
adhesiveness for solids or semi-solids and absorptiveness (for liquids) in proportion to
the varying intensities of light. A bite or tooth is given to the film by immersing it
in a bath of bichromate of potash, hypochlorate of potash or suitable substance and
the plate is ready for printing.
For relief processes the film is treated with hot water or strongly alkaline or acid
solutions to give the requisite relief.
The extreme surface of the film is very liable to give an abnormal effect all over,
from exposure to the developing liquid, and other causes, I therefore use a very thin
covering film or other means to prevent this. I also use an opaque support for the
film or if of glass may expose it in the camera the reverse way about, so that the
luminous image falls upon the under surface of the film or I use a porous support and
expose only the under side of the film to the developer. 1 also use water colors as
well as greasy pigments or materials, and the image developed is not necessarily a
negative but may be a positive.
oil of January 1888

page_text: Improvements in Photo-mechanical Printing.
1, ERNEST HOWARD FARMER, of the Polytechnic School of Photography, 309 Regent
Street, in the County of Middlesex, Photographer, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
I have discovered that an ordinary sensitive gelatino-argento-bromide or other
silver emulsion film can after exposure be developed in such a way as to produce
degrees of adhesiveness or absorptiveness in proportion to the varying intensities of
light, and that it will then give immediately, by ordinary printing methods, prints in
either aqueous or greasy pigments.
Here I would remark that it has before been proposed in a Specification No. 143981
to employ such plates in photo-mechanical printing. The method consisted in
rendering the film insoluble to varying depths by exposure to light and subsequent
developement; reversing the film to another support soas to present its under side or
surface and in dissolving away so much of the film as remained soluble thereby
obtaining a surface in which the parts are more or less raised in direct proportion to
the intensity of the light to which they have been exposed.
My method however does not involve the removal by solution of any part of the
film which hoth before and after exposure is undissolved in the liquid which I apply
neither is the reversing process required and the surface of the plate which I produce
is raised highest or is most absorptive and softest in the parts which have been least
exposed to the influence of light.
I find it to be requisite when employing silver emulsion plates in photo mechanical
printing to guard against an abnormal action of the surface layer of the film which is
liable, even in the parts on which the light has not operated, to undergo a change when
brought into contact with the developer.
To avoid this I either carry the film upon paper or other porous support and apply
the developer on the under side. Or I apply a protective covering over the film.
"
When operating in accordance with my invention although a result can be obtained
on an ordinary gelatine plate, it is better to specially prepare the plates.
An emulsion is prepared of a character which gives an image of a clear and
crisp nature, and containing a large proportion of silver haloid.
6 grammes of clear gelatine are placed in clean spring or filtered water, and when
thoroughly softened, are dissolved in 2000 grammes (c. c.) of water heated to a tem-
perature of 150° F. The solution is then filtered, and if not already acid to test paper
is slightly acidified with hydrochloric acid 100 grammes of crystallized silver nitrate
are dissolved in 2000 grammes of distilled water.
SO grammes of potassium bromide are also dissolved in 2000 grammes of spring
water, and the solution slightly acidified with hydrochloric acid.
The gelatine solution at a temperature of from 140° to 150° F. is placed in a large
perfectly clean pan, and the potassium bromide and silver nitrate solutions, also at
a temperature of from 140° to 150° F. are poured alternately, in quantities of

page_text: 250 grammes at a time, into the gelatine solution, the latter being constantly stirred
to hasten the complete incorporation of the three liquids.
When the admixture is complete, a little of the emulsion, placed on a glass plate,
and examined by the light transmitted throngh it, from a candle or gas flame, should
appear a bright orange or ruby red colour.
The emulsion is next placed in a plated copper, or glass vessel, standing in a water
bath, and digested with constant stirring at the temperature of 212° F. (boiling
water) until on being examined on a piece of glass in the aforesaid manner, the
colour of the emulsion is blue, violet, or grey; the time usually occupied for the
change being from 60 to 100 minutes-1000 grammes of bromine water are prepared
by shaking up a small quantity of bromine with 1000 grammes of water placed in a
glass bottle. The emulsion being cooled to 140° F. is replaced in the pan and with
gentle stirring the 1000 grammes of bromine water are added to it.
The sensitive silver haloid and a portion of the gelatine will now settle to the
bottom of the pan. The liquid is poured away and the solid residue is washed in
several changes of water until free from bromine and soluble salts. It is then again
placed in the copper or glass vessel with sufficient water to cover it, heated rapidly in
the water bath to 212° F. and kept at that temperature with stirring for a few
minutes, or until the whole of the solid mass has melted and re-emulsified.
All subsequent operations must be performed in the dark room.
90 grammes of soft gelatine which have been thoroughly swelled are squeezed to
free them from adhering water, are added to the emulsion (which has been removed
from the hot bath) and stirred with it until dissolved and uniformly incorporated.
70 grammes of powdered gum arabic and 20 gramines of glycerine are dissolved
in 1000 grammes of warm water (100° F.) and the mixture added to the emulsion,
together with sufficient warm water to make a total bulk of 2000 grammes (2 litres).
The whole mass is then thoroughly stirred until homogeneous.
The emulsion is now finished and after filtering through pure washed flannel is
ready for preparing the films.
Some sheets of polished plate glass, after perfect cleansing, are coated with talc in
the manner usual for enamelling and are slightly warmed in front of a fire.
They are placed upon perfectly level supports and coated with the emulsion, which
should be quite free from air bubbles or dirt. The emulsion is spread evenly over the
surface of the glass and then allowed to set. For plates 60 × 50 centimetres, about
150 cubic centimetres of emulsion are required. As soon as the emulsion has set on
the glass, sheets of paper (preferably Rive's) which have been evenly swelled by
damping are lowered on to the surface of the emulsion and the whole placed in a
warm air chamber to dry.
When dry the emulsion should leave the glass with a highly polished and smooth
surface and should adhere firmly to the paper.
After exposure in the camera or by contact the damped film is floated, paper side
downwards, on a pyrogallol solution or developer containing a proportion of alcohol.
A good developer contains-
Pyrogallol
Ammonia 880
Potassium bromide
Water (distilled)
Alcohol
The above mixture is poured into a dish
1 gramme
1 c. c. (cubic centimetre)
⚫5 gramme
180 c. c.
20 c. c.
having an inner slightly raised edge all
round until it overflows the inner edge. The film is then immediately lowered upon
the surface, paper downwards.
As soon as the portions of the film where the shadows will be are seen to soften and
glisten, the film is lifted off the developer and lowered upon a pad of bibulus paper.
Or instead of floating the film, its surface may be rubbed over with a waxing solu-
tion (to prevent its getting wetted by the water) and immersed in the developer.
Glass or flint is crushed and filtered through a lawn sieve; it is moistened with a

page_text: 1 per cent solution of wax in benzole (wax 1 gramme, benzole 1000 c. c.) and stirred.
until dry. It is then kept in a bottle the neck of which is covered with a piece of
lawn. for use as required.
The film which has been taken off the wet developer is now dusted with the glass
which permeates or sinks into the film in proportion to the intensities of light. The
film (together with the paper which still supports it) is lastly laid upon a polishod
copper or zinc plate previously coated with gum, dried with (or without) the aid of
heat, and the powdered glass brushed off.
The surface will now be found grained or etched in relief, in exact proportion to the
varying intensities of light which fell upon the portions of the film during the
exposure.
To print-from this surface I prefer to proceed in the following manner :-
I warm the plate and rub over the surface with sweet oil and turpentine on a rag.
1 then dab ink on plate with flannel and clean off the surface with the palm of the
hand using whiting at the finish. I again warm the plate and drag ink smoothly
over the surface and finally put the plate through a roller press with damped paper
on top.
Although the grained or etching process as above described is preferred it admits of
further simplification as follows the metal plate is coated direct with the emulsion
from which the second portion of gelatine is omitted. The plate after exposure is
developed with a developer containing alcohol the surface wiped and the plate heated
until the film is seen to swell and soften.. The glass or other coarse powder is dusted
over and the plate is treated as before.
Instead of dusting with the powdered material a roughened surface may be
applied with pressure to the film so that indents are produced in proportion to its
relief or softness.
Or without the application of glass powder or the like the plate may be used for
printing by other printing processes in which the swelling or softening of a film are
utilised.
When I desire to avail myself of the absorptiveness of the sensitive surface in order
by its aid to prepare an etched plate I prefer to proceed as follows:-
A copper plate is covered with a graining film in the ordinary way and is then
coated with the emulsion (from which the gum arabic is omitted) and is dried.
The dried plate is dipped in a solution of soluble gum containing a very small
quantity of undigested silver bromide and again dried. After exposure the plate
intended to be etched is developed by immersion in the pyrogallol developer, washed
and then treated with the ordinary (Ferric Chloride) etching solution.
When the etching is complete the film is removed and the plate is retouched ready
for printing in the ordinary way of printing from etched plates.
The treatment with soluble gum with a little undigested silver bromide as mentioned
above is for the purpose of forming a covering to the surface layer of the film such
as will prevent the abnormal action of the developer upon this layer to which reference
has already been made. This precaution is applicable with advantage to the process
previously described in which the emulsion is applied direct to the plate, and not only
to this process but in all cases where the circumstances are such that the developer
cannot conveniently be applied on the under side of the film.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what
I claim is
1. The improvement substantially as described in photo-mechanical printing con-
sisting in the production of a printing plate or surface by the aid of a silver emulsion
film and a developer which leaves the parts of the filu on which the light has least
operated in a swollen or absorptive state and graduated in accordance with the
intensity of the light so that the parts of the film least exposed to light become raised
above or more absorptive than the parts which have been more exposed as herein set
-forth.

page_text: 2. The improvement substantially as described in photo-mechanical printing con-
sisting in the production of a printing plate or surface by applying to the surface of
a silver emulsion film after developement, a fine pulverulent material such as powdered
glass or a surface in grained relief in such manner that the same adheres or penetrates
more or less in proportion to the intensities of the light to which the different portions
of the film have been exposed as herein set forth.
3. The improvement substantially as described in photo-mechanical printing con-
sisting in the production of a printing plate or surface by coating a plate with a
silver emulsion film, transferring the same to a surface of paper or like material,
exposing the film (after insulation) on its under side to a developing solution and
producing a more or less grained or indented surface in accordance with the exposure
as herein set forth.
4. The improvement substantially as described in photo-mechanical printing con-
sisting in the production of a printing plate or surface by applying a silver emulsion
film to a plate on which an etching ground has been previously laid, then exposing
the film, afterward applying etching solution over the film and so as to bite the
picture into the plate as herein set forth.
5. The improvement substantially as described in photo-mechanical printing con-
sisting in the production of a printing plate or surface by the aid of a silver
emulsion film and a developer applied to the under side of the said film as herein set
forth.
6. The improvement substantially as described in photo-mechanical printing con-
sisting in the production of a printing plate or surface by the aid of a silver emulsion
film provided with a soluble surface covering of gum or like material protecting the
surface layer of the film and preventing its abnormal action as herein set forth.
7. My improvements in photo-mechanical printing substantially as herein described.
Dated this 12th day of October 1888.
CARPMAEL & Co.,
Agents for the Applicant.