Improvements in the Manufacture of Photographic Plates and Films.
Year: 1895

page_text: Date of Application, 11th Feb., 1895
Complete Specification Left, 9th Nov., 1595-Accepted. 14th Dec., 1895
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Photographic Plates and Films.
I, CHARLES FREDERICK OAKLEY of Pall Mall Factory, Parchmore Road,
Thornton Heath in the County of Surrey, Works Manager to R. W. Thomas and
Company Limited, do hereby declare the nature of this invention to be as
follows:
--
My invention has reference to the manufacture of photographic plates and
films, and its object is the prevention of the effects generally known as halation.
For the purpose of preventing halation it has been proposed at various times
during the last 6 or 8 years to coat the glass plate, film or other support for the
sensitive emulsion with a layer or substratum containing a coloring matter which
renders the said layer or substratum non-actinic,-the said coloring matter subse-
quently disappearing during the development or fixing. But these colored
substrata have failed to answer in practice because the coloring matters which they
contain are of such a nature that they become to a great extent taken up by the
surperposed coating of emulsion, the sensitiveness of which is consequently
seriously impaired and sometimes practically destroyed.
It has also been proposed with the object of preventing halation, to coat the
glass plates or other supports with two or more coats of emulsion of graduated
degrees of sensitiveness, but these plates, besides being expensive, have not been
found altogether satisfactory.
Now the object of my invention is to cover the glass plate or other support with
a layer or substratum colored with such a material and in such a manner that the
coloring matter will not be subsequently taken up by the sensitive emulsion applied
to the plate over the substratum; the sensitiveness of the emulsion therefore not
being affected.
According to my invention, I first coat the glass plate or other support with a
solution of gelatine, albumen or the like. I then immerse the plate, preferably
when dry, for a sufficient length of time say from two to five minutes more or less,
in a solution of a material of suitable color and of such a nature that it will not
only color the layer of gelatine and render it non-actinic by entering into the
substance of same, but also produce a reaction which will have the effect of
hardening the gelatine and rendering it practically insoluble, thereby preventing
the coloring matter from being taken up by the emulsion subsequently applied.
A substance which I have found to answer this purpose is permanganate of potass.
On removing the plate from the solution I wash it in cold water, then allow it to
dry, after which I coat it with the sensitive emulsion, and I leave this to dry in a
dark room.
The color in the substratum disappears during the developineut when developers
such as hydroquinone are employed, or in the fixing bath when this contains
sulphite of soda and acid.
Dated this 11th day of February 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.

page_text: Improvements in the Manufacture of Photographic Plates and Films.
I, CHARLES FREDERICK OAKLEY of Pall Mall Factory, Parchmore Road,
Thornton Heath, in the County of Surrey, Works Manager to R. W. Thomas and
Company Limited, 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 :-
My invention has reference to the manufacture of photographic plates and
films and its object is the prevention of the effects generally known as halation.
For the purpose of preventing halation it has been proposed at various times
during the last 6 or 8 years to coat the glass plate, film or other support for the
sensitive emulsion with a layer or substratum below the sensitive emulsion this
layer or substratum containing a coloring matter which renders it non-actinic, the
sail coloring matter subsequently disappearing during the development or fixing.
But these colored substrata have failed to answer in practice because the coloring
matters which they contain are of such a nature that they become to a great
extent taken up by the superposed coating of emulsion the sensitiveness of which
is consequently seriously impaired and sometimes practically destroyed.
It has also been proposed with the object of preventing halation to coat the glass
plates or other supports with 2 or more coats of emulsion of graduated degrees of
sensitiveness but these plates besides being expensive have not been found
altogether satisfactory.
Now the object of my invention is to cover the glass plate or other support with
a layer or substratum colored with such a material and in such a manner that the
coloring matter will not be subsequently taken up by the sensitive emulsion applied
to the plate over the substratum; the sensitiveness of the emulsion therefore not
being affected.
My invention consists in the manufacture of photographic plates and films by
first coating the glass plate or other support with a solution of gelatine or other
suitable non-sensitive material, then immersing the plate preferably when dry for a
sufficient length of time say from 2 to 5 minutes more or less in a coloring and
hardening solution, then after washing the plate and allowing it to dry coating it
with a sensitive emulsion. The coating of sensitive emulsion should be allowed to
dry in a dark room. The coloring and hardening solution must be one that will
not only color the layer of gelatine and render it non-actinic by entering into the
substance of same but also produce a reaction which has the effect of oxidizing
and hardening the gelatine and rendering it practically insoluble. Consequently
the coloring matter is prevented from being taken up by the sensitive emulsion
subsequently applied. The solution preferably employed for the purpose is
permanganate of potass and a suitable strength is obtained by adding about i ounce
of the permanganate to 1 gallon of water.
The color in the non sensitive substratum disappears during the development
when developers such as hydroquinone are employed or in the fixing bath when
this contains sulphite of soda and acid.
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 1
claim is :-
1. The manufacture of photographic plates and films by first coating the glass
plate or other support with gelatine or other suitable non-sensitive material, then
immersing the support in a solution of permanganate of potass or other material
which will color the gelatine and render it non-actinic by entering into the substance

page_text: of same and also harden the gelatine and render it practically insoluble and there-
fore prevent it giving up its coloring matter to the sensitive emulsion, and then
coating the support with a sensitive emulsion, substantially as and for the purpose
hereinbefore described.
2. As a new article of manufacture a photographic plate or film consisting of a
support having two coats the first coat being a non-sensitive material which has
been colored and rendered non-actinic and practically insoluble by immersion in a
solution of permanganate of potass after its application to said support, and the
second coat being a sensitive emulsion, substantially as set forth.
Dated this 8th day of November 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.