HOW THE CELLULOID FILM IS MADE
I have already shown how the perseverance and ingenuity of Eastman and
Walker aided in solving the problem of animated photography. Their film
was used for the first time experimentally in the United States as far
back as 1889, although it did not enter the general market until about
two years later. From that time there was an increasing demand from
the host of experimenters for large quantities of the narrow, thin
sensitised strip of celluloid. As the demand increased the chemists
associated with the subject redoubled their efforts; their product was
still far from perfection, and even to-day they will admit that many
abstruse problems remain to be unravelled.
Although the present-day consumption of celluloid film for
cinematograph purposes is enormous, aggregating several million feet
per week, the manufacturing process is of such a peculiar character
that the number of firms identified with its production can be counted
upon the fingers of one hand. In the United States it is controlled by
the Eastman Kodak Company, who have extensive factories at Rochester
in the State of New York, and a large establishment at Harrow in
England. In France Messrs. Lumière and Sons, and in Germany the
Gaevert firm, have large factories. British effort is represented by
the Austin-Edwards Company, which produces an excellent film, but the
home industry is in its infancy. The three first-named firms supply
almost the entire demand. The Eastman firm has the largest output,
about 3,500,000 feet per week, which is due to the fact that in the
United States there are over 14,000 picture palaces open every day from
morning until midnight, and many large firms engaged in the preparation
of the film subjects. Most of the Eastman supply is used in the United
States and Great Britain. Aside from it and the French and German
products, some of the large European film producers prepare their own
stock, as the celluloid base is called. If all these totals were added
together, the sum of them would show something like 6,000,000 feet of
film, in both negatives and positives, consumed every week.
Each country has millions of pounds invested in the enterprise. It is
difficult to gauge the proportions of the entire industry. If all its
varied branches are taken into consideration, it probably ranks as one
of the largest in the world. And the whole of this development has
taken place within twenty years.
In order to gain an idea of one branch of the industry, the manufacture
of the film, one must pay a visit to the extensive works of the
Eastman Company, the plant of which is able to turn out no less than
7,200,000 lineal feet of film for moving pictures every week--truly a
tremendous output. This capacity has not been taxed to the utmost yet,
but when the requisite machinery was laid down, the company decided
to anticipate the future. Should the present pace of development be
maintained, there is no doubt that, before the end of another twenty
years, this firm will find its present installation barely sufficient
to meet the demand. Continued chemical research and improvement of
processes is tending to reduce the cost of the material, and while at
the same time the moving picture business itself is expanding on all
sides, fresh markets are constantly being opened up for the products of
the manufacturers.
At the Eastman works is to be seen a striking illustration of the
growth in the manufacture of celluloid film. In the room where the
ingredients are mixed together there is a small barrel, which will
hold 500 pounds of the film mixture. This little barrel, together with
another of the same capacity, sufficed to meet all requirements in the
year 1891. In the same building is a battery of fifty huge barrels,
each with eight times the capacity of the small one, and these are run
night and day to meet the present demand for the material. The little
barrel is no longer used; but it is preserved as an honoured relic
of the past and an eloquent witness of the tremendous growth of the
film-manufacturing industry for cinematography.
The ingredients for the film are gun-cotton, known technically as
pyroxylin, and wood alcohol. The pyroxylin is prepared by treating
cellulose devised from such vegetable materials as flax or cotton
waste, with a mixture of sulphuric and nitric acids. The ingredients
are associated in large cylindrical tanks ranged in long rows
upon the upper floor, and discharged through trap doors into the
barrels beneath. The gun-cotton is then dissolved in the alcohol by
mechanically rotating the huge barrels. It is possible to treat in this
way some 200,000 pounds of material at one time. The mixing process
reduces the gun-cotton and wood alcohol to a viscous liquid of the
consistency of extracted honey, which substance forms the base of the
film, or support for the sensitive emulsion, and is known technically
as cellulose-nitrate.
When the gun-cotton has been dissolved to the requisite degree, the
syrup-like mixture is drawn from the barrels and stored in cylindrical
tanks.
The next step is the conversion of the mixture into sheets of the
requisite thinness. It is not rolled out, but poured upon suitably
polished supports, and spreads out, like varnish, in a thin film. The
Eastman patent specifies three distinct kinds of receptacle for the
pouring process: a long sheet of polished glass, an endless polished
metallic belt, and a revolving drum having a highly polished surface.
Any of the three will produce the result; and in each case the deposit
has to be permitted to dry to a certain degree.
[Illustration:
[_By permission of the Eastman Kodak Company._
THE DISSOLVING ROOM.
The ingredients for the celluloid film are dissolved in large tanks.
The liquids are drawn off and led through the trap doors into in-mixing
barrels.]
When the drying is achieved, the thin coating of transparent flexible
material, resembling a skin, is stripped from its support and
coated with the sensitive emulsion. The latter is of two degrees
of sensitiveness, according to whether the film is to be used
as a negative or a positive. The former is of the very highest
sensitiveness to light that it is possible to obtain, since under
normal circumstances it is only exposed for the fraction of a second;
while the film required for the positive, which is used for projection,
is rendered less sensitive, as it can be given a longer exposure in the
printing operation.
[Illustration:
[_By permission of the Eastman Kodak Company._
THE MIXING BARREL.
This picture conveys a striking impression of the growth of the film
manufacturing industry. Two small barrels, each holding 500 pounds,
made all the film base or “dope,” as it is called, in 1891. The larger
barrel behind holds 4,000 pounds.]
The base, with its sensitised coating, is now permitted to become
dry and hard. At the conclusion of this operation the length of thin
celluloid sheeting, technically called a web, which is about 3½ feet
wide, is slit into strips of the standard width now used in all
cinematograph cameras and projectors--1⅜ inches wide.
Extreme care has to be taken to secure a uniform thickness. The plant
at the Rochester works has reached such a degree of accuracy that the
thickness of the film which is taken from the polished rolls, although
the web measures 2,000 feet in length, does not vary above the standard
by more than 1/4,000th part of an inch.
As I have already said, however, after all this care, the product is
far from being perfect, and it sometimes displays strange caprices.
They are most pronounced in the tropics. Owing to the volatile
character of the ingredients employed in its manufacture, the film
undergoes considerable shrinkage in hot climates owing to evaporation.
I have seen film shrunk so much that it failed to conform with the
standard gauge, and the teeth of the sprocket in the printing machine,
instead of engaging with the holes, played upon the outer smooth
edges of the film. To maintain the prime condition of the film it is
necessary to keep it somewhat moist, and accordingly the packing boxes
carry a certain amount of damped material. But in tropical countries
where the heat is intense, it is by no means a simple matter to keep
the film in condition; and for this reason it is often difficult to
secure satisfactory pictures of scenes in tropical countries. A firm
which dispatched an operator to Central America to secure a series
of scenic and industrial films failed to obtain a single length of
pictures worth showing. I saw the results of the expedition. The film
was badly distorted, and the pictures in some instances were so thin
or indistinct as to defy projection. £500 ($2,500) had been expended
without result.
There is another eccentricity displayed occasionally by some films in
tropical climes, which is difficult to explain. An operator will expose
several hundred feet of film, which, when developed, fails to show the
slightest sign of exposure. I have seen the results of a first-class
cinematographer working between the limits of Capricorn and Cancer. His
films when developed were as clear as if they had never been exposed
to the action of light. The firm took one section of the exposed film
and re-exposed it on a London street. It showed on development the
image of London traffic, being as bare of any other image as if it had
never seen the jungle. Heat and dry atmosphere seem to exercise some
obscure chemical action, which prevents the sensitive surface of the
films from being affected by exposure; yet when the film is returned to
a naturally moist climate, like that of England, it appears to recover
its original qualities.
As the component parts of a cinematograph film are of an inflammable
nature, the resultant fabric is naturally also highly inflammable.
This danger in the early days severely menaced the development of
the industry, especially since those occupied in projection were
careless of the most elementary precautions. The film, after passing
through the lantern, fell a dishevelled mass into a basket, where it
formed a tangled heap of thin combustible material, as inflammable
as petrol-soaked shavings. Celluloid emits a vapour of an explosive
nature, and it is always dangerous to use a naked light in its close
proximity. Yet custom rendered the operator heedless of the danger.
The outcome was inevitable. Legislation stepped in and ordained that
the projector should be encased in a steel fire-proof chamber for the
protection of the public. The result was that the cinematograph was
barred from many places where the magic lantern was used.
[Illustration:
[_By permission of the Eastman Kodak Company._
A BATTERY OF CELLULOID MIXERS.
Fifty barrels, holding 200,000 pounds of the “dope,” are run
continually day and night.]
Moving pictures could not be shown at such establishments as schools,
merely because they did not possess a fire-proof chamber in which
to operate them. A non-inflammable film was, of course, the next
demand. To attempt to render celluloid non-combustible was akin to
rendering gunpowder non-explosive. An absolutely new film-base had
to be found. Cellulose as a basic constituent could not be dispensed
with--in fact, chemical research has not yet succeeded in discovering
an efficient substitute. Efforts were concentrated upon the treatment
of the cellulose in such a manner as to prevent it being readily
combustible, with the resultant production of the preparation known
as cellulose-acetate, which is practically non-inflammable. But while
this substance complies with the letter of the law and does not burst
into flame, it does melt, however, under the influence of heat, and in
so doing sometimes emits copious clouds of smoke, which are capable of
producing panic in an audience quite as readily as an outburst of flame.
[Illustration:
[_By permission of the Eastman Kodak Company._
THE LIQUID CELLULOID STORAGE ROOM.
When the ingredients are mixed thoroughly the syrup-like mass is stored
in cylindrical tanks until required by the machines to be made into the
film. Each vessel is of five tons capacity.]
Under ordinary circumstances, this non-inflammable film is quite safe
to handle, and from that point of view is adapted for the purpose
of exhibiting in buildings where a special chamber is not provided.
The heat produced by the focussed rays in the lantern, or the
inadvertent contact of a naked light, do not promote combustion. The
cellulose-acetate merely chars or melts, the action being purely local.
The celluloid film is supplied generally in lengths of 165 feet, which
is approximately the capacity of the average film box. The actual
picture itself upon the film measures one inch in width by ¾ of an inch
in depth.
The question naturally arises as to what becomes of the films which
have passed through their allotted span of life. When the celluloid
film was first placed on the market this material was of a certain
value. The sensitised gelatine emulsion was stripped off, and the base
was converted into varnish. But this practice has fallen into disuse.
Practically speaking, old films have no economic value. As a rule
they are burned. If the junk film is obtained in sufficiently large
quantities, a slightly remunerative by-product can be obtained in the
form of metallic silver from the ashes, but the yield is so small and
silver is so cheap that the trouble involved does not pay unless the
waste is destroyed in tremendous bulk.
This is the era of the profitable utilisation of waste products, and
no doubt a large fortune is awaiting the chemist who succeeds in
evolving a cheap process for turning the useless cinematograph film to
commercial account. Newspapers, old iron, and other metals, rubber,
sawdust, and even garbage, possess a certain economic value, and there
is no reason to suppose that used celluloid film is an exception to
this general rule of utilising waste products. One by-product, as we
have pointed out, is certain of reclamation--the silver--but the other
constituents might prove just as valuable if a cheap, inexpensive
method were contrived for their commercial reclamation.