Improvements in and connected with Photographic Films.
Year: 1898

page_text: Reprinted
as amended in accordance with the decision of the Comptroller General,
dated the 20th day of September 1899.
Date of Application, 23rd Nov., 1898-Accepted, 4th Feb., 1899
COMPLETE SPECIFICATION (AMENDED).
Improvements in and connected with Photographic Films.
We, OSWALD MOH, of Augustastrasse, Görlitz, Germany, Manufacturer, ADOLF
HESEKIEL, of 32, Landsbergerstrasse, Berlin, Germany, Chemist, and JULIUS
GRÜNEWALD, of 112A, Friedrichstrasse, Berlin, Germany, Banker, 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 :-
The present invention has reference to photographic films and is of great utility,
both for amateur and professional photographers. According to this invention a
sensitized film may be exposed in the known manner, developed, fixed and washed as
usual and then strengthened (that is to say rendered thicker) with a gelatine film by
pressing the two films together in a moist condition.
There is thus obtained a
strengthened negative sheet or film which may be treated like any other negative
sheet, but can be copied from both sides with the same sharpness. The photographic
image is produced in the camera upon an improved negative paper which we will
now describe. This negative paper comprises a suitable sheet of paper as a carrier
for the sensitized film, which film consists in turn of three different films viz.-
(1) A rubber film which rests directly on the paper to which it adheres;
(2) A collodion film intimately united to the rubber film.;
(3) An upper gelatine film as a carrier for the sensitizing material.
These three films together constitute the negative sheet or film of which the
paper serves as the carrier. The negative paper thus constituted is exposed to
light in the camera.
In the following description the combination of the negative sheet or film with the
paper will always be referred to as "the negative paper."
After the negative paper has been exposed in the camera, developed, fixed and
washed, it is dried, and it then possesses the property of allowing the negative film
to be stripped from the paper backing. The rubber film adheres sufficiently firmly
to the paper to permit the various operations of developing, washing and so on,
yet not so firmly as to prevent the stripping off of the sheet; a smooth and easy
removal of the negative film from the paper is thus possible. The negative sheet
thus obtained is rather thin and liable to pucker or form wrinkles, which is a
hindrance in copying. In order to remedy this drawback the negative sheet is
preferably strengthened, i.e. rendered thicker. For this purpose a gelatine paper
of similar constitution to the negative paper above described, but with this
difference that its gelatine layer contains no sensitizing material, is immersed in
water and united to the original negative while this is still upon its paper
The two negative
backing, so that both gelatine filins adhere to each other.
papers are then pressed into intimate contact by rolling or other suitable operation,

page_text: and the resulting sheet is hung up to dry. After drying, the two paper backing
sheets between which the strengthened negative film is contained inay be stripped
off, and a stronger, thicker and smooth negative film is thus obtained which does not
roll up and can be copied from both sides.
Besides the strengthening effect referred to, a further useful effect is produced by
the employment of an adherent sheet as just described. The rubber film of the
second or strengthening negative paper which rubber film is in direct contact with
the paper, receives an impression of the grain of the paper. It is thus possible by
choosing a suitable paper to impart any desired grain to this rubber film. The
grain thus imparted to the rubber film may thus serve as a substitute, either wholly
or partially, for retouching, since the rays of light are dispersed and distributed in
copying by the grain. Inequalities or ruggedness of the image or picture are thus
suppressed by means of the dispersion of the rays of light by the grain without
loss of any of the characteristics of the picture. The sheet of different grain secured
upon the original or sensitized sheet thus acts as a substitute for the slow and
tedious operation of retouching the negative. With a little easy touching up,
results may be obtained equal to those of artistic photography and such as have
hitherto only been obtained by tiresome and tedious labour. It is evident that the
strengthening film must be selected in varying thickness according to the size of
work. It is further obvious that for a landscape a strengthening film with little
or no grain should be employed. In the case of portraits the coarseness of the
grain would increase with the size of the head in order to obtain the right effect.
The employment of the negative paper herein described for the production of
negatives obviates the drawback occasioned by the necessity of rendering the
negative to be copied transparent with oil which has hitherto existed because
according to the present invention the paper backing is stripped from the negative
sheet and is no longer present when the copying is effected. A great improvement
as regards the strengthening, i.e. the thickening of the negative sheet, is that the
two moist gelatine films, which have been sinoothly and completely united to their
backing sheets prior to pressing them together, return to their original size after
pressing, regularly and without forming blisters or turning or curling over; a com-
pletely flat sheet is the result. A further advantage is that the negative sheet is
completely protected during drying from dust and dirt by means of the superposed
paper.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is:-
1. A method-of-manufacture-of-films-for-photographic purposes, which method
consists-in-superposing-upon-a-paper-bucking cheet a-rubber-film, then-covering-the
rubber film-with-a-collodion film, and finally covering-the-collodion-film--with-a
gelatine-film, the outer or gelatine-film-serving as a carrier for the sensitizing
medium, the film, after-exposure in the camera and after developing, fixing, washing
and-drying, being adapted-to-be-stripped-from-the-backing sheet, substantially as
described.
2. An-improved-film-for-taking photographie-negatives,
1. 3. The method of producing a strengthened negative film, which method con
sists in pressing together a negative sheet or film such as that specified in-Claim-2,
composed of a detachable backing, a rubber film, a collodion film and a sensitized
gelatine film, substantially as described, after it has been exposed in the camera,
developed, fixed and washed, and a second film or sheet of similar constitution to-that
specified-in Claim-2; but containing no sensitizing medium, both sheets being in a
moistened condition, and the pressure being so effected that the gelatine films adhere
firmly together, while the backing sheets enclosing the strengthened negative thus
formed may be stripped off after drying, substantially as herein before described.
2. 4. In the method of strengthening the negative specified in Claim 1
the selection of the backing sheet for the strengthening film with a definite grain,

page_text: which grain becomes transferred to the rubber film of the strengthening film, with
the object of producing by this grain of the strengthening film, a dispersion of the
light in copying, and thus to dispense either entirely or partially with retouching,
substantially as described.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.