Improvements in or relating to the Manufacture of Photographic Films.
Year: 1889

page_text: Date of Application, 10th Dec., 1889-Accepted, 26th Apr., 1890
COMPLETE SPECIFICATION.
Improvements in or relating to the Manufacture of Photographic
Films.
A communication from GEORGE EASTMAN, of Rochester, in the County of Monroe,
and State of New York, United States of America.
I ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.1.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 :-
This invention relates to the manufacture of the improved flexible film produced
in the manner and having the characteristics hereinafter described.
In practising this invention a clear fluid solution of nitro-cellulose or gun-cotton
and camphor is first made by dissolving said materials in one or more of the known
liquid solvents, such for example as methyl-alcohol which is preferably used because
of its active solvent properties. To remove all unconverted or imperfectly dissolved
substances from, and to clarify the solution it is preferred to filter it through fine
cotton cloth, the object being to obtain a solution which will be perfectly clear and
which can be readily spread in a thin layer or film upon the surface of a level glass
plate or other rigid supporting surface and which when dry will be photographically
structureless.
Such a fluid solution may be produced by dissolving 9000 grains of soluble gun-
cotton or nitro-cellulose and 5400 grains of camphor in 112 ounces of methyl-
alcohol.
It has been found that when such solution is spread out in the form of a film and
dried as the process of drying is accompanied with the evaporation of the more
volatile constituents the mass shrinks and its exposed surface is liable to become
pitted or covered more or less with small depressions and that it is otherwise liable to
prove objectionable. To obviate this it is preferable to add to the solution made
according to the above formula say 28 ounces of fusil oil and also preferably though
not necessarily 7 ounces of amyl-acetate or any equivalent agent which produces the
same effect.
The proportions above given for the solid and liquid constituents of the solution
may be varied, as well as the proportions of fusil oil and amyl acetate according to
circumstances but those which are above given have been found to give satisfactory
results.
The dissolving of the solids may be hastened and the products rendered more
uniform by the application of gentle heat with occasional agitation the process.
being conducted in a closed vessel to prevent loss by the evaporation of the volatile
constituents. :
Having made the clear liquid solution mentioned the next proceeding is to obtain
a thin layer or film of the same by depositing and spreading the solution upon a rigid
supporting surface. For this purpose it is preferred to use a flat table or bed
plate of plate glass or other material having either a polished or dead surface
and on the surface of which the solution may be spread by means of a suitable
spreader moving longitudinally over the said table.
It has however been found that when the fluid solution is applied directly to
and dried on the clean surface of the table or bed-plate it adheres so firmly to
the said table that the subsequently formed complete photographic film can be
removed only by the application of considerable force which sometimes results
in the tearing of it or in its being stretched unequally so that it will buckle and
be nnfitted for use in roll holders and for negative making.
To overcome this difficulty the surface of the glass or other rigid supporting

page_text: ..
surface before the fluid solution is spread thereon is rubbed over or coated with a
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. After
the bed-plate or table has been so prepared a thin layer or film of the fluid
solution of nitro-cellulose.and camphor in methyl-alcohol is spread evenly upon it.
The preliminary coating of wax solution should be of a character to weaken
without preventing the adhesion to the glass surface of the supporting film as
is very desirable that this supporting filn when dry should adhere throughout its
whole under surface to the rigid supporting surface until the photographic film is
to be removed.
The next operation which must be performed in a photographic dark room is to
apply to the surface of the supporting film a suitable sensitized medium such as
fluid gelatino argentic emulsion in the form of a thin uniform layer or film but
experience has shown that unless special provision is made against such a con-
tingency this sensitized film will not adhere at all points to the supporting film
but will be detached or separated at parts and thus form blisters in the photo-
graphic film.
This it has been ascertained is due in part at least to the greasy character of
the surface of the supporting film to remove which such surface is washed preferably
with clear water to which has been added from 2% or 3% of a binding agent
such as silicate of potash or silicate of soda. After the surface of the film support
is again dry the layer or film of gelatino argentic emulsion is spread evenly upon
the washed surface and will be found to adhere uniformly. The spreading of the
sensitized film may be effected by the same apparatus as is used for spreading
the supporting film.
The supporting film and sensitized film which combined together, are herein
termed the photographic film, are retained in place upon the rigid supporting
surface until the sensitized film has dried, when the photographic film may if
desired be cut into strips of suitable width and it is then ready to be removed
or stripped from the said rigid supporting surface which may be effected by means
of a traversing roller.
The film for supporting the sensitized film is necessarily made quite thin,
ordinarily from 3 to 5 one-thousandths of an inch in thickness or about the thickness
of the paper supports heretofore generally employed in ordinary roll holders.
A photographic film produced as described is of such thickness and flexibility
that it can readily be wound upon the spools of ordinary roll holders, such as the
Eastman-Walker roll holders, and manipulated for exposure in the latter.
The
supporting film or backing for the sensitized film is of a material unaffected by
moisture, of uniform density, free from striae and buckles and photographically
structureless, and the photographic film as a whole is capable of being used for
all those photographic purposes for which can be used glass plates with sensitized
films in ordinary cameras or paper with similar films in roll holding cameras.
Having now particularly described and ascertained the nature of this said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is
1. The herein-before described improvement in the art of producing flexible
photographic films, which consists in first applying a fluid solution of nitro-cellulose
and camphor in a layer or film upon a rigid supporting surface, then drying the same,
said film being photographically structureless when dry and of sufficient strength and
stiffness to properly support and sustain a suitable sensitized film through all the
operations of negative making and printing positives therefrom; then spreading
thereon while still upon said rigid supporting surface a thin layer or film of gelatino
argentic emulsion; then drying the same while still on said rigid supporting surface;
then stripping the photographic film from said support; such photographic film when
dried and stripped being of such a thickness as to be flexible enough to be wound
upon the rollers of and used in ordinary roll holders.

page_text: 2. The herein-before described improvement in the art of producing flexible
photographic films, the same consisting in depositing upon a rigid supporting
surface a fluid solution of nitro-cellulose and camphor spreading the same into a film
of substantially uniform thickness but having the surface in a flat plane, drying said
film while still in contact with said rigid supporting surface, thereby producing its
uniformity of surface and causing it to adhere closely to said rigid supporting surface,
said supporting film being photographically structureless when dry; applying a thin
layer or film of fluid gelatino argentic emulsion to the said dried and adherent
supporting film by spreading said emulsion progressively from end to end of the
previously drie supporting film, drying said film of emulsion while the supporting
film is still adhering closely to the rigid supporting surface, and finally detaching or
stripping the photographic film from the rigid supporting surface preparatory to
winding the same upon spools; said photographic films being sufficiently flexible when
dried to be wound upon the rollers of and used in ordinary roll holders and to be
manipulated in the latter for exposure.
3. The herein-before described improvement in the art of forming flexible photo-
graphic films, which consists in first making a fluid solution of nitro-cellulose and
camphor; second, filtering such solution; third, depositing and spreading the saine
in a film upon a rigid supporting surface and allowing the volatile constituents to
evaporate while the supporting film is adhering to the said rigid supporting surface,
said supporting film being photographically structureless when dry; then applying an
even layer or film of fluid sensitized emulsion to the surface of the supporting film,
while still adhering to the rigid supporting surface and finally drying said sensitized
film and stripping the photographic film from its support.
4. The herein-before described improvement in the art of forming flexible photo-
graphic films, which consists in first making a fluid solution of nitro-cellulose and
camphor; second, filtering such solution; third; depositing and spreading the same
in a film upon a rigid supporting surface and allowing the volatile constituents to
evaporate while the supporting film is adhering to the said rigid supporting surface,
said supporting film being photographically structureless when dry; then applying
an even layer or film of fluid sensitized emulsion to the surface of the supporting
film while still adhering to the rigid supporting surface and finally drying said
sensitized film and stripping the photographic film from its support by means of a
traversing roller.
5. The herein-before described improvement in the art of forming flexible film
supports, which consists in adding fusil oil to a fluid solution of nitro-cellulose and.
camphor, and subsequently depositing and spreading such solution upon a rigid
supporting surface and drying it.
6. The herein-before described improvement in the art of forming flexible film
supports, which consists in combining methyl-alcohol, camphor, nitro-cellulose and
fusil oil to form a fluid solution and then depositing and spreading the latter upon a
supporting surface and drying the same.
7. As an improvement in the art of producing flexible film supports, the herein-
before described improved step in the process, which consists in forming the fluid.
solution, of a mixture of methyl-alcohol, fusil oil, nitro-cellulose and camphor, to form
a fluid solution for spreading in a thin film upon a support.
8. As an improvement in the art of producing flexible film supports, the addition
of amyl-acetate to a fluid solution of nitro-cellalose and camphor in a liquid solvent,
and the subsequent depositing and spreading of said solution in a film upon a supporting
surface and drying the film upon the latter.
9. As an improvement in the art of producing flexible film supports with smooth
surfaces, the same consisting in combining fusil oil and amyl-acetate with nitro-
cellulose camphor and a fluid solvent, and subsequently spreading the fluid solution in
a thin layer or filin upon a supporting surface and drying the said film, preliminary
to the application of a film of gelatino-argentic emulsion.
10. The herein-before described improvement in the art of forming flexible photo-

page_text: graphic films from 'a fluid solution of nitro-cellulose and camphor, the same consisting
in first applying a solution of wax to the supporting surface; depositing and
spreading the fluid solution in a thin layer or film upon said surface; drying the
supporting film thus formed; spreading a thin layer of gelatino-argentic emulsion
upon the dried supporting film and drying the same; and finally stripping the photo-
graphic film from the support upon which it was formed.
11. The berein-before described improvement in the art of forming flexible
photographic films, which consists in applying an even layer or film of a fluid
solution of nitro-cellulose and camphor to a flat surface by means of a spreader
moving longitudinally of the same, evaporating the volatile constituents to dry said
layer or film and subsequently while said film is adhering to the flat surface upon
which it was first deposited applying a fluid sensitized emulsion to its exposed surface
by means of a travelling spreader, drying said sensitized film and finally stripping the
photographic film from the flat surface.
12. The herein-before described improvement in the art of forming flexible
photographic films, the same consisting in 'first forming a layer or film of a solution
of nitro-cellulose and camphor by spreading such solution upon the flat and rigid
support, evaporating the volatile constituents to dry said film and cause the same to
adliere firmly to said flat support, applying a film of sensitized emulsion upon the
exposed surface of said film support and drying said film of emulsion, dividing
the photographic film into strips while still attached to its flat support and then
winding said strips upon a roller or rollers to strip said photographic film from its
support.
13. The herein-before described improvement in the art of forming flexible
photographic films, the same consisting in depositing and spreading a fluid solution
of nitro-cellulose and camphor upon a supporting surface in the form of a thin layer
or film, and drying the same; then washing the face of the dried film support; then
spreading upon the surface of said film support a film of fluid gelatino argentic
emulsion and drying the same; and finally stripping the photographic film from its
support.
14. The herein-before described improvement in the art of forming flexible
photographic films, the same consisting in depositing and spreading a fluid solution
of nitro-cellulose and camphor in a thin layer or film upon a plate or surface previously
coated with a solution of wax; drying said film support; washing the exposed
surface of said film support; then spreading a thin layer or film of fluid gelatino-
argentic emulsion upon said film support and drying the same; and finally stripping
the photographic film from its support.
15. The manufacture of photographic films substantially as specified.
W. P. THOMPSON & BOULT,
Agents for the Applicant.