Improvements in the Process of Manufacturing Thin Sheets of Nitro-cellulose.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in the Process of Manufacturing Thin Sheets of
Nitro-cellulose.
I, EDMUND NEVILLE TODD, of 35 Clinton Avenue, Newark, New Jersey, United
States of America, Manufacturer, do hereby declare the nature of my invention for
"IMPROVEMENTS IN THE PROCESS OF MANUFACTURING THIN SHEETS OF NITRO-
CELLULOSE" and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
In carrying out my invention, 1 dissolve soluble pyroxyline or nitro-cellulose in the
various of the well-known solvents mixed with the various well-known menstrua, thus
making a thin collodion, varnish, or solution of pyroxyline or nitro-cellulose, and
sometimes a solution of nitro-cellulose and camphor.
I prefer to use as a compound solvent acetate of amyl, acetate of methyl, fusel-oil,
and oil of camphor, in which I dissolve the pyroxyline or nitro-cellulose. I desire to
use the several ingredients in the following proportions, the same being in the propor-
tion of one-half pound of nitro-cellulose or pyroxyline to one gallon of the mixture of
acetate of methyl, acetate of amyl, fusel oil, and oil of camphor, the several ingredients
being in the proper proportions as follows:-8 oz. of nitro-cellulose or pyroxyline to
64 oz. of acetate of methyl, 32 oz. of acetate of amyl, 24 oz. of fusel oil and 8 oz. of
oil of camphor. If desirable, camphor may be added in the proportion of two ounces
of camphor to one gallon of the solvent. I do not wish to be understood as limiting
myself to the exact proportions here stated, for I may change this compound solvent
or any of its ingredients; or, if desirable, under certain eircumstances I may use
other solvents, and the above mentioned compound solvent may be employed in
various proportions of its ingredients. Having thus prepared this collodion or varnish,
the process of manufacturing the thin and transparent sheets or nitro-cellulose or
pyroxyline for photographic or other purposes is accomplished by the use of the
apparatus described in the accompanying drawing, in which the figure shown is a
vertical section of the device employed.
In said drawing, a is a tank or receptacle, provided at the top thereof with a
removable cover b and in the inclined bottom with a spigot or valve c. Within this
receptacle, preferably near the top thereof, is arranged one or more bars or rods d,
upon which are hung or suspended plates of glass or other material e by means of
hooks f; or said plates may be secured in said receptacle in any other convenient
manner. These plates having been arranged in the receptacle a, the solution men-
tioned in the foregoing description hereto is then gently poured into said receptacle
until the plates of glass are almost entirely immersed in the solution of collodion or
varnish, and the same is then allowed to remain at rest for a short time until all the
air has escaped and all air-bubbles have disappeared and the liquid solution remains
quiet. As soon as the liquid within the tank has become quiet and all signs of air-
bubbles on the surface thereof or on the plates have disappeared, the cover 6 is placed
upon the receptacle a and the liquid allowed to remain quiet.
It is very essential that the plates e be suspended at their upper ends from the
rods d, as thereby when the solution is poured into the receptacle the air-bubbles will
rise to the top of the liquid, and there is no danger of any air adhering to the sides of
the plates, as is the case in apparatus where the plates are arranged in horizontal
positions when the air has not been previously exhausted from the receptacle by means
of an air pump.
Furthermore, when the liquid is being slowly drawn off through the spigot in the
bottom, the same will be gradually lowered and will slowly pass down the sides of the
plates, thereby resulting in a very thin and even coating adhering to said plates, which
can easily be removed when dry in thin and transparent sheets of nitro-cellulose of
uniform thickness.

page_text: The cover b is provided with an outlet or pipe g passing to the roof of the building,
through which pipe all disagreeable odours and gases of fumes escape without
endangering the health of the operator.
When the liquid collodion or varnish has remained within the tank the required time
to thoroughly forun an even coating over the suspended plate, the spigot or valve in
the botton is opened and the liquid is allowed to flow slowly into the receptacle h
placed beneath the spigot where the solution is stored until again required during the
next process of coating the plates.
By means of the spigot or valve I can regulate the flow of the liquid from the
tank
a, causing the same to escape gradually therefrom until said tank is entirely
emptied.
The great advantage thus attained is that by regulating the flow of liquid collodion
from the receptacle or tank a, I accomplish as a new result, the production of a thin
and even coating on the plates of glass or other material, which coats are free from
any blemishes or air-bubbles.
While the solution is very slowly and gradually being withdrawn from the bottom
of the tank a and the level of the solution is becoming lower and lower, the solvents
in that small part of the solution adhering to the plates evaporate, thereby leaving a
very thin film of nitro-cellulose adhering to the surface of the plates, which as it
becomes exposed dries quickly and evenly, as is evident. When all the liquid has
been drawn off from the receptacle, the coated plates of nitro-cellulose or pyroxyline
are allowed to remain within the receptacle a until the coating thereon is thoroughly
dried, free from dust, thereby resulting in the production of an even and perfect film
of nitro-cellulose or pyroxyline on said plates.
Another great advantage is attained in that when the plates are removed from the
tank the material thereon is perfectly dry, and dust will not adhere to the material
and become impregnated with the saine, as in the case with plates taken from the
solution and put up to dry in another apartment, as is done in the old processes.
As has been stated in the above, the solution is drawn off by the spigot or valve in
the bottom of the receptacle into a closed vessel placed beneath the same and stored
therein for further use.
After having drawn off the solution and when the coating upon the plates has
become perfectly dried, said plates are taken from the receptacle and the films of
nitro-cellulose or pyroxyline adhering to the plates are stripped therefrom, and the
latter again returned to the tank, ready for the next process.
The films of nitro-cellulose removed from both sides of the plates of glass or other
material are thin and of uniform thickness and are cut up into various sizes of
sheets, ready for sale to the consumer.
It will be understood that I do not wish to limit myself strictly to the use of
the apparatus shown in the drawing, for although the same may be of a desirable
construction my process can readily carried out in like manner by employing
apparatus of different construction without departing from the scope of my invention.
If desirable, the solution may be first poured into the receptacle a, and the
plates of glass or other material may then be immersed in said solution, as will be
understood.
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 I
claim is
1. The process of manufacturing thin transparent sheets of nitro-cellulose or
pyroxyline, which consists in pouring a solution of collodion or pyroxyline or nitro-
cellulose into a receptacle having arranged therein vertically suspended plates of
glass or other analogous material, allowing said solution to remain quiet for a time
in said tank, drawing off the said solution very slowly from the bottom of the tank,
and thereby causing a thin film of solution to adhere to the plates directly above
the level of the gradually receding solution, the solvents in said adhering film
evaporating and causing the film to dry evenly and quickly and to form upon said
J

page_text: plates as the solution is being withdrawn from the tank, an evenly distributed film
forming a thin and transparent sheet, as set forth.
2. The process of manufacturing thin transparent sheets of nitro-cellulose or
pyroxyline, which consists in placing in a closed receptacle or tank, vertically
arranged plates of glass or other material, pouring into said receptacle a solution
of nitro-cellulose, pyroxyline or collodion, placing a cover on said receptacle,
allowing the solution therein to remain at rest and the escape of the air and fumes
through an outlet in said cover, then very slowly drawing off the said solution
from the bottom and thereby causing a thin film to adhere to the plates directly
above the level of the gradually receding solution, the solvents in said adhering
film evaporating and causing the said film to easily and quickly dry, and whereby, as
the solution is being withdrawn, an evenly distributed film is produced, forming
a thin and transparent sheet on the surfaces of the vertically arranged plates, as
set forth.
Dated this and dan 1000
EDMUND NEVILLE TODD.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.