Improvements in Sensitized Coatinuous Films for Photographic and Cinematographic Purposes
Year: 1899

page_text: "Improvements in Sensitized Coatinuous Films for Photographic
and Cinematographic Purposes."
I, JOHN TYACK SANDELL of 215. Selhurst Road, South Norwood, London, S.E.
Photographic Chemist; do hereby declare the nature of this invention to be as
follows:-
My invention relates to the manufacture of films for the roll holder or for use in
the cinematograph and has for its object to avoid the well known objections to the
use of celluloid as the support for the sensitive surface especially the liability of
deterioration after exposure and danger of ignition with heat.
My invention consists in overcoming these objections either by dispensing with
all extraneous support for the sensitized emulsion and manufacturing a film suitable
for the roll holder of the ordinary camera or for the cinematograph wholly of gelatine
emulsion suitably hardened to render it self-supporting and impart the tensile
strength necessary for its use as a continuous film in the roll holder or cinemato-
graph or by using for its support a material free from the objections to the use of
celluloid.
The film of my invention may be produced in the one case by coating a suitable
surface either with a single coating of emulsion of suitable thickness or with two,
three, or more coatings superposed until the requisite thickness and strength are
obtained (said superposed coatings being preferably of graduated degrees of sensi-
bility as and for the purpose specified in a previous Patent granted to me dated
7th December 1891 No. 21, 381) the coating being afterwards stripped from the
surface on which it is applied, and used without any adventitious support in the
camera. Or the film may be produced by coating a support of hardened gelatine
either with a single coating of emulsion or with several superposed coatings of such
emulsion, said coatings being of graduated degrees of sensitiveness.
When the film is used without any support as first described, a hardening agent
such as an alum or formic aldehyde is incorporated with the emulsion whilst when
a gelatine support is used such a hardening agent would be incorporated both with
the support and with the emulsion.
1000
A. M. & WM. CLARK
Chartered Patent Agents.
53. Chancery Lane. London.

page_text: "6
COMPLETE SPECIFICATION (AMENDED).
Improvements in Sensitized Continuous Films for Photographic
and Cinematographic Purposes."
I, JOHN TYACK SANDELL of 215, Selhurst Road, South Norwood, London. S.E.,
Photographic Chemist; 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 relates to the manufacture of films for the roll holder of the ordinary
camera or for use in the cinematograph and has for its object to avoid the well
known objections to the use of celluloid as the support for the sensitive surface,
especially the liability of deterioration after exposure and danger of ignition with
heat.
My invention consists in overcoming these objections by dispensing with all
extraneous support for the sensitized emulsion and manufacturing a film wholly of
gelatine emulsion suitably hardened to render it self-supporting and to adapt it for
use as a continuous film in the roll holder or cinematograph.
The film of my invention is produced by coating a suitable surface by means of
the well known apparatus employed in the manufacture of dry plates either-with a
single-coating of emulsion-of a-thickness sufficient-to-afford-the-necessary-tensile
strength, or with two, three, or more superposed coatings of graduated degrees of
sensitiveness as and for the purpose specified in a previous Patent granted to me
dated 7th December 1891 No. 21,381; and of a thickness sufficient to afford the
necessary tensile strength the coating (whether single-or-multiple) being afterwards
stripped from the surface on which it is applied, and used without any adventitious
support. The surface upon which the coating-or coatings of emulsion is-or are thus
applied is preferably that of a sheet or strip of glass perfectly flat and highly
polished; and in order that the film may possess the hardness necessary to render
it self-supporting, a hardening agent such as an alum or formic aldehyde is in-
corporated in sufficient quantity with the emulsion.
The proportion of the hardening agent will depend upon the initial state of hard-
ness of the gelatine used in the composition of the emulsion, this hardness varying
within somewhat wide limits in the case of different parcels of gelatine as supplied
by manufacturers of that article. Generally speaking, however, about one and
one-half per cent by weight of chrome alum relatively to the weight of gelatine used
in the emulsion, will suffice.
It is to be observed that the use of a hardening agent as described is of importance
as tending to facilitate the manufacture of the films by accelerating the setting and
drying of the emulsion-whether-the-film-be-formed-of-one-or-of several superposed
coatings of the emulsion, it being of course necessary in-the-latter ease to allow
one coating to become thoroughly dry before a further coating is applied.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
The production of sensitized continuous films for photographic and cinemato-
graphic purposes wholly of sensitized gelatine emulsion and a hardening agent.
substantially as specified.
Dated this 10th day of October 1899.
A. M. & WM. CLARK
Chartered Patent Agents,
53, Chancery Lane. London.