Improvements in or relating to Films or Supports for Photographic Negatives, or Prints.
Year: 1889

page_text: Second uition.
The decision of the Law Officer, of the 25th day of October 1894. allowed,
under Section 18 of the Patents, &c., Act, 1883, an Amendment of This
Specification.
[Communicated from abroad by FREDERICK CRANE, of Short Hills, New Jersey,
United States of America, Manufacturing Chemist.]
Improvements in or relating to Films or Supports for Photographic
Negatives, or Prints.
.
J, JOSEPH SINCLAIR FAIRFAX, of 433, Strand, in the County of London, Patent
Agent, do hereby declare the nature of this invention to be as follows:
This invention, as communicated to me by my foreign correspondent, relates to the
films or supports used for photographic negatives, or prints.
66
Heretofore it has been customary to form the sensitized gelatine film used in the
production of photographic negatives, and commonly known as dry plates," upon
transparent glass. The increasing use of the dry plate process for out-of-door photo-
graphy has added to the demand for a light plate which will reduce to a minimum
the weight to be transported.
Paper has been used as a temporary support: the sensitized film being laid upon it
in long strips, and apparatus provided, by which rolls of this film can be placed in the
camera, unrolled without opening the camera, and successive plates exposed. This
improvement has lessened weight, but on account of the want of transparency in the
paper, it has been found necessary after exposure and development to separate the
film from the paper, and coat the film with collodion. The pyroxyline support, thus
provided, requires skill to apply, and any accident destroys the picture on the nega-
tive; while it has been found impracticable to thus secure anything but a very light
and unsubstantial support.
Attempts to substitute pyroxyline for paper, in the first instance, have not proved
successful; the strips of celluloid or plastic compounds of pyroxyline, (either rolled or
split thin), having insufficient flexibility for use on rolls. It has also been found
impracticable to form these pyroxyline supports by means of ordinary collodion; the
film which could be formed from a single application, (unless the liquid when applied
was too thick to flow), being too unsubstantial, and subsequent applications injuriously
acted upon or dissolved the previously formed film; moreover, the great contraction
of collodion in drying was objectionable.
My improvement utilises the good qualities of pyroxyline, (when thoroughly dis-
solved, and provides a transparent or translucent, substantial, unchangeable, flat and
flexible photographic negative support. This support has no resilience, and hence,
if wound on a roller, has no tendency to unwind; or if unwound, has no tendency
to curl.
To secure as thick a film as possible, with one application, I make a mixture of
pyroxyline with resin or with gum resin, oleo resin, balsams, gelatine, or a mixture of
pyroxyline with any two or more of the said substances, in any liquid or solvent, or

page_text: mixtures thereof that will dissolve all of the base; employing as small a proportion of
pyroxyline as is consistent with the cohesiveness and strength of the film to be used
for the support. In addition to the greater body which can be secured by each
application of a solution, thus compounded, the resulting film or support is smoother,
less inclined to curl and the film can be reinforced with additional coatings of the
solution with less risk of injury to the previously formed film. I may also render the
liquid still more innoxious by making it nearly saturated; a course which I am very
careful to pursue when using pyroxyline alone for my base, and by this means I am
enabled to apply successive coats of a pure pyroxyline varnish which it has not here-
tofore been found practicable to do. In practice, however, for the reasons heretofore
mentioned, I prefer a mixed base to one of a pure pyroxyline.
Having thus outlined the invention, I will proceed more particularly, by way of
illustration, to describe some methods of applying it. I do not, however, wish to be
understood as confining myself to particular methods of application, since there are
various ways which involve merely such modifications of the solution as will suggest
themselves to those skilled in the art.
A good solution may be made of the following:-
'
60 gallons of propyl, butyl, or amyl acetate; or mixtures thereof.
15 gallons of camphor or other essential oils.
25 gallons of methyl or ethyl alcohol.
100 pounds of shellac.
37 pounds of pyroxyline.
This solution is allowed to flow upon glass, (preferably first coated with a thin
solution of india-rubber in benzine, to prevent adhesion), and when dry it is stripped
from the glass and cut into the desired size; or, for use on long strips of gelatine
to be used from rolls, for which purpose my invention is especially adapted. For
this purpose, I distribute my solution upon the gelatine film, or I first form it on
paper, the paper having been properly prepared so that the film will not adhere
thereto, strip it therefrom, and then, or before stripping, distribute the gelatine
upon my film. These distributions may be made from cylinders revolving in a
trough or receptacle filled with the solution, to be applied in any of the well-
known ways.
The following formula will serve as an example of a solution composed of
pyroxyline:-
-
100 gallons of methyl alcohol, or amyl, propyl, or butyl acetate, or
inixtures thereof.
50 pounds of pyroxyline.
This solution is so nearly saturated that the second application of the solution,
(which generally is necessary in order to secure a sufficiently thick and substantial
support), will not destroy nor injure the previously formed film. If for any reason
I wish to use less pyroxyline, or to use stronger or more energetic solvents, I may
reduce the surplus or too active solvent power by the substitution of miscible non-
solvents in sufficient quantity to neutralise the excess of solvent.
It is to be understood that I do not confine myself to the particular solvents
named, which are enumerated as examples. Any of the well-known solvents, and
well-known non-solvents, may be employed. The choice of these depends upon the
time required for the film to set or dry. The use of miscible non-solvents will
depend upon the amount of unemployed solvent power which it may be desirable
to reduce.
My invention may also be used as a support for photographic prints, especially in
the production of transparencies.
Dated this 26th day of June 1000

page_text: COMPLETE SPECIFICATION (AMENDED).
Improvements in or relating to Films or Supports for Photographic
Negatives, or Prints.
1, JOSEPH SINCLAIR FAIRFAX, of 433, Strand, in the County of London,
Consulting Engineer and Patent Agent, do hereby declare the nature of this
invention to be as follows:-
This invention, as communicated to me by my foreign correspondent, relates to
the films or supports used for photographic negatives, or prints.
"
Heretofore it has been customary to form the sensitized gelatine film used in the
production of photographic negatives, commonly known as dry plates," upon
transparent glass. The increasing use of the dry plate process for out-of-door
photography, has added to the demand for a light plate, which will reduce to a
minimum the weight to be transported.
Paper has been used as a temporary support: the sensitized film being laid upon it
in long strips and apparatus provided by which rolls of this film can be placed in the
camera, unrolled without opening the camera, and successive plates exposed. This
improvement has lessened weight, but on account of the want of transparency in the
paper, it has been found necessary, after exposure and development, to separate the film
from the paper, and coat the film with collodion. The pyroxyline support, thus
provided, requires skill to apply, and an accident may destroy the picture on the
negative while it has been found impracticable to thus secure anything but a very
light and unsubstantial support.
i.
Attempts to substitute pyroxyline for paper in the first instance, have not proved
successful; the strips of celluloid or plastic compounds of pyroxyline, (either rolled
or split thin), having insufficient flexibility for use on rolls. It has also been found
impracticable to form these pyroxyline supports by means of ordinary collodion;
the film which could be formed from a single application, (unless the liquid when
applied was too thick to flow), being too unsubstantial; while subsequent applications
injuriously acted upon or dissolved the previously formed film. Moreover, the great
contraction of collodion in drying was objectionable, as it caused the film to buckle.
The improved film or support may be made from a thin solution of pyroxyline,
flowed upon a smooth surface, called a carrier," and the thickness regulated by
the number of coats, when, by using a nearly saturated solution, I am enabled to
apply successive coats of this pure improved pyroxyline compound, which, hereto-
fore, has not been done. It may be made also, from a very heavy solution of
pyroxyline, and spread upon the carrier, the thickness being regulated by the
spreader. In practice I prefer to use the heavy solution and spread it, as it is
more quickly done, and cheaper than by flowing. In making these solutions, I use
as a solvent any liquid or solvent which will thoroughly dissolve the pyroxyline,
and will not give the film a greasy surface to which the gelatine emulsion will not
adhere nor injuriously affect the gelatine emulsion when applied. In the heavy
solution it is preferred to use gum camphor as one of the solvents, and I mix with
the solution any of the miscible non-solvents, such as amyl alcohol, butyl alcohol,
and petroleum naphtha, which, while having little or no solvent power in themselves
are often desirable ingredients in these solutions from their water repellant qualities
and cheapness.
Having thus outlined the invention, I will proceed, more particularly by way of
illustration, to describe some methods of applying it. I do not, however, wish to be
understood as confining myself to the particular methods of application mentioned,
as there are various other ways which involve merely such modifications of the
solution as will be readily suggested to those skilled in the art.

page_text: 1
For a thin solution to be flowed upon glass, or other polished carrier, the following
is found to be a good formula :
40 gallons of methyl (or wood) alcohol.
20 gallons of amyl, propyl, or butyl acetate, or mixtures thereof.
40 gallons of amyl alcohol.
50 pounds of soluble pyroxyline.
The solution is so nearly saturated that the second application thereof (which is
frequently necessary to secure a sufficiently thick and substantial support), will not
destroy nor injure the previously formed film. The solution is allowed to flow upon
glass, (preferably first coated with a thin solution of india rubber in benzine, or other
suitable coating to prevent adhesion), and when dry it is stripped from the glass or
other carrier, and cut to desired sizes, or into long strips to be used from rolls, for
which the invention is especially well adapted.
For a heavy solution, to be spread upon the carrier by a spreading knife or straight
edge, the following formula is a good example:
55 gallons of methyl (or wood) alcohol.
20 gallons of amyl alcohol or fusel oil.
25 gallons of amyl acetate,
50 pounds of gum camphor.
100 pounds of soluble (photographic) pyroxyline.
For amyl alcohol in the forogoing formulas, butyl alcohol or its isomer may be
substituted, and for the amyl acetate, the acetate of butyl or other ethers of butyl
alcohol and amyl alcohol which are known solvents of pyroxyline may be substituted.
Also, the proportions in which the liquids are mixed will somewhat depend upon the
amount of dampness in which they are to be worked, the degree of solvency of the
pyroxyline employed, the consistency of the solution desired, and the amount of
susceptibility to water required in the film.
The solution given in the last example is too heavy to flow, but it is distributed
upon the glass or other polished carrier (prepared as before mentioned) by means
of a knife or other equivalent device, as is well understood, and when the film has
set or hardened, I strip it from the carrier and cut it into plates or long strips to be
used from rolls.
After taking the pyroxyline film from the glass or other carrier, I distribute upon
it the sensitized gelatine emulsion from cylinders revolving in a trough containing
the emulsion, or in any of the well known ways of distributing the emulsion upon its
support. Or I may distribute the sensitized gelatine emulsion by spreading it upon
the pyroxyline film before its removal from the glass or other carrier. After being
coated with the gelatine emulsion, the strips of coated films are placed in holders,
or rolled upon rollers, and are then ready for use in the camera.
If, for any reason, it is found desirable to use less pyroxyline, or to use stronger
or more energetic solvents in any of the solutions named, the surplus or too active
solvent power may be reduced by the substitution of miscible non-solvents in sufficient
quantity to neutralize the excess of solvent, the amount of these non-solvents to be
used in any case depending entirely upon the amount of unemployed solvent power
which is desirable to reduce.
It is to be understood that I do not confine myself to the particular solvents named,
which are enumerated as examples. For instance, in place of, or in conjunction with,
amyl alcohol, or fusel oil or butyl alcohol or their isomers, I sometimes use benzoline
or petroleum naphtha or benzoline.
It is necessary, however, to use about the proportions named of non-hygroscopic
menstrua to prevent clouding the resultant film, but in general, any of the well-
known solvents and well-known non-solvents may be employed, provided they are
not of such a greasy nature as to prevent the adherence of the sensitized emulsion
to the finished film; and the choice of these depends upon the time required for the
film to set or dry.

page_text: This invention may also be used as a support for photographic prints, especially
in the production of transparencies.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that I do not
claim any mirtures in which amyl acetate or its equivalent is not used but, that what I
claim is:
1. A transparent or translucent flat and flexible photographic negative support,
consisting of a solidified solution of pyroxyline but subject to the disclaiming note
combined with a sensitized gelatine emulsion, substantially as described.
2. A transparent or translucent flat and flexible photographic negative support
consisting of a solidified solution of pyroxyline but subject to the disclaiming note
combined with a sensitised gelatine emulsion, and formed in strips or lengths
suitable for use in a camera by exposure therein from rolls, substantially as
described.
3. A transparent or translucent flat and flexible photographic negative support
consisting of a solidified solution of pyroxyline, obtained from a liquid or plastic
mixture therefore containing petroleum naphtha, butyl acetate or amyl acetate and
gum camphor, combined with a sensitized gelatine emulsion, substantially as
described.
Dated this 25th day of April. 1890.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.