Improvements in Photographic Films.
Year: 1890

page_text: Date of Application, 2nd Dec., 1890-Accepted, 3rd Jan., 1891
Improvements in Photographic Films.
A communication from GEORGE EASTMAN, of Rochester, County of Monroe, State of
New York, United States of America, Manufacturer.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E., 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 :-
Difficulty has heretofore been found in using photographic film such for instance
as is described in Letters Patent No. 19897 dated 10th December 1889 granted to
me, composed of a film support made from a compound of nitro-cellulose camphor
and other substances and having applied thereto after being dried, a film or layer
of gelatino-argentic emulsion especially if the photographic film be wide, owing to
the tendency of such film to contract at the edges inore than the central parts' so
that it will not lie flat on the table or support of the roll-holder such for instance
as that of the Eastman and Walker roll-holder, but when strained tight, the edges
alone will be brought in contact with the table, while the central parts will bulge
and buckle thereby rendering it objectionable or unsuitable for photographic purposes.
This unequal contraction and buckling is believed to be due to the drying out
or evaporation of the volatile substance or substances used with the nitro-cellulose to
make the compound from which the film support is produced and which remain in
it after it is dried. One reason for this belief is that it has been observed that such
photographic film that has been kept on spools for some time becomes permanently set
and the buckling is more marked.
It has been discovered that by coating and thus protecting or sealing the film
support on both of its surfaces with some material such as gelatine (which it is believed
prevents, retards, or modifies the evaporation of said substance or substances in the
film support when dried) the film is prevented from unequally contracting or buckling
to an objectionable extent and is caused to remain in good condition and so that it
may be kept in rolls or on spools for a considerable period of time without materially
changing thus enabling it to be employed in all cases where paper films are used. I
shall call these coatings herein "sealing coatings."
In the accompanying drawings:
Fig. 1 is an enlarged sectional view of a photographic film containing this inven-
tion and
Fig. 2 a side view of one form of apparatus that may be employed in making the
same.
Referring to Figure 1 the letters A indicates a translucent or transparent film
support preferably made from a compound of nitro-cellulose camphor and other
substances as described in the said Letters Patent No. 1989789.
( is what I shall term the back sealing coating on the back of the film support A
composed preferably of translucent or transparent gelatine preferably rendered
insoluble in water by any suitable material such as chrome-alum. B is what I shall
term the front sealing coating preferably made of sensitive gelatino-argentic emulsion
such as is commonly employed in the photographic art.
I will now describe one method which my correspondent has successfully employed
to make the photographic film containing the discovery or invention.
A solution is first prepared of hard white gelatine in the proportion of about
10 grains of the gelatine to an ounce of water which I heat to about 100 degrees
Fahrenheit, and then add thereto sufficient of an aqueous solution of 10 grains to the
ounce of chrome-alum to render the gelatine insoluble when dried the amount of
chrome-alum solution required varying with the quality of the gelatine which can be
CD 17

page_text: readily ascertained by a few trials as is well understood it varying from about two
ounces to three ounces per gallon of the gelatine solution.
I then flow or spread this gelatine solution upon a rigid supporting surface such as
plate glass in a thin layer or film care being taken to secure contact with said surface
and to prevent the formation of bubbles between it and the gelatine solution after
which the gelatine while on this support is dried and forms the back sealing coating.
A thickness of 2000 to 1000 of an inch for this coating has been found when dry
satisfactory but this may vary.
If this gelatine solution be applied directly to the perfectly clean surface of a glass
plate and then dried while on said surface and the subsequent operations hereinafter
described to make the complete photographic film are performed it will be found to
adhere so firmly to said surface that it can be removed only by application of con-
siderable force, sometimes resulting in the tearing of the photographic film or
stretching it unequally so that it will buckle and be unfitted for use in roll-holders or
for photographic purposes. To facilitate the removal or stripping of the photographic
film the surface of the glass plate or other rigid supporting surface is rubbed or coated
with a very weak solution of mineral wax in benzine or other suitable solvent or a
weak solution of beeswax or with any other equivalent agent to produce the same
result before spreading the gelatine solution upon said surface. This preliminary
coating should be of a character to weaken without preventing the adhesion of the
back sealing coating to the rigid supporting surface as it is very desirable that it
should adhere throughout its whole under-surface to such supporting surface during
the application thereto and the drying of the other coatings hereinafter described and
until the photographic film is ready for removal and use.
I then flow upon this back sealing coating, after it is dried and while still adhering
to the rigid supporting surface a thin layer or film of a fluid compound of nitro-
cellulose camphor and other substances made substantially in the manner set forth
in the said Patent No. 1989789 which is then dried forming what is termed the film
support which adheres firmly to the back sealing coating and forming what I shall
term the film support. A thickness of Too of an inch for this film support has been
found when dry satisfactory but this may vary. Upon this film support is then
coated or spread a thin layer or film of sensitive gelatino-argentic emulsion which
is dried. A thickness of 1000 of an inch for this film has been found when
dry satisfactory but this may vary. Before this latter layer or film is applied I
prefer to wash the surface of the film support with clear water to which has been
added a binding agent as described in said Letters Patent No. 1989789.
After the photographic film has thus been completed and dried it is stripped from
the rigid supporting surface preferably by detaching one end and applying it to a
suitable winding device.
In another application filed by me No. 19896 A.D-1889 is described in detail an
apparatus capable of being used to perform the various flowing or spreading operations
that I have described including the stripping of the completed photographic film
from the rigid supporting surface upon which it is made.
In Fig. 2 of the accompanying drawings is illustrated an apparatus capable of
being used for flowing or spreading the various layers or films composing the
photographic film. In said figure E indicates a rigid support formed preferably of
glass, Fa hopper or receptacle for containing the various solutions and spreading
them successively upon one another as described having a suitable adjustable gate
and spreader. and being propelled longitudinally on the rigid support by suitable
means such for instance as a travelling pitch chain G having a projection 9 adapted
to engage a corresponding projection on the receptacle, but as this apparatus forms
no part of the present invention further description of it is unnecessary.
It is
described more at length in said Letters Patent No. 189878.
The photographic film containing this invention will lie practically flat on the
table or support of the roll-holder or frame in which it may be employed and the
edges will not contract and its surfaces will not buckle to an objectionable extent
even after being kept for a considerable period of time in a roll or on a spool.

page_text: A preferred manner of carrying out or embodying in a photographic film this
discovery, has been described above, but I do not wish it to be understood that my
correspondent restricts himself thereto as there are many other ways of embodying
or carrying out this invention some of which I will now describe.
Thus, instead of the film support being made of a fluid compound of nitro-cellulose,
camphor and other substances such as are set forth in said Letters Patent No. 1989789
it may be made from a compound containing nitro-cellulose or a substitute therefor, and
other substances that have a tendency to evaporate when the film support is dried. So,
also, instead of making the front sealing coating of sensitive gelatino-argentic
emulsion, it may be made from the same gelatine solution that has been described
the back sealing coating can be made of, and then the sensitive emulsion described
or a collodion or other sensitive emulsion may be applied thereto after it is dried
and while the back sealing coating and film support are upon the rigid supporting
surface. So again instead of using a solution of gelatine for the sealing coatings,
they may be made from substitutes therefor such as albumien solutions made insoluble
in water when dried, that will produce substantially the same effect in preventing
the unequal contracting or buckling of the film support or of that and the sensitive
coating. Again although I prefer to employ a translucent or transparent back
sealing coating it may be opaque and arranged so that it may be stripped off or
removed therefrom.
All the operations of flowing or coating of the different layers or films, and
stripping of the completed photographic film from the supporting surface on which it
is formed may be effected by different means from that described.
Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to me by my foreign correspondent, and in what manner the
same is to be performed, I declare that what I claim is :-
1. As a new article of manufacture a flexible film support containing when dried
a volatile substance combined with a sealing coating on each of its sides.
2. As a new article of manufacture a photographic film consisting of a flexible film
support containing a volatile substance combined with a sealing coating on one side
and with a sealing coating which is photographically sensitive on the other side
substantially as described.
3. As a new article of manufacture a photographic film consisting of a flexible film
support containing a volatile substance combined with a sealing coating on one side
and with a sealing coating of sensitive gelatino-argentic emulsion on the other side
substantially as described.
4. As a new article of manufacture a photographic film consisting of a flexible film
support containing a volatile substance combined with a sealing coating of insoluble
gelatine on one side and with a sealing coating of sensitive gelatino-argentic emulsion
on the other side substantially as described.
5. As a new article of manufacture a photographic film consisting of a flexible film
support containing a volatile substance combined with a sealing coating on each side
one of said coatings carrying photographically sensitive material substantially as
described.
6. As a new article of manufacture a flexible film support composed of a nitro-
cellulose compound containing a volatile substance such as camphor combined with
a sealing coating on each of its sides substantially as described.
7. As a new article of manufacture a photographic film consisting of a flexible film
support composed of a nitro-cellulose compound containing a volatile as camphor
combined with a sealing coating on one side and with a sealing coating which is
photographically sensitive on the other side substantially as described.
8. As a new article of manufacture a photographic film consisting of a flexible film
support composed of a nitro-cellulose compound containing a volatile substance as
camphor with a sealing coating on one side and with a sealing coating of sensitive
gelatino-argentic emulsion on the other side substantially as described.
9. As a new article of manufacture a photographic film consisting of a flexible

page_text: support composed of a nitro-cellulose compound containing a volatile substance as
camphor combined with a sealing coating of insoluble gelatine on one side and with
sealing coating of sensitive gelatino-argentic emulsion on the other side substantially
as described.
a
10. As a new article of manufacture a photographic film consisting of a flexible
film support composed of a nitro-cellulose compound containing a volatile substance
as camphor combined with a sealing coating on each side one of which coatings
carries photographically sensitive material.
Dated this 2nd dox of Desemba 1800
W. P. THOMPSON & BOULT,
Agents for the Applicant.