Barton County democrat. [volume] (Great Bend, Kan.) 1885-1915, 1893-05-18
CELLULOID FILMS.
Some Interesting Information Concerning
Their Manufacture.

Some Interesting Information Concerning
Their Manufacture.
Ce11uloid, which is comparatively
new product, dating back only to 1869,
has come to be of immense importance
in the arts. 1t is a hard, durab BILE sub
stance, almost entirely unaffected by
acids and allalies, Interchangeable under
ordinary atmospheric conditions, and is
very tough. 1t is rendered plastic by
heat and can be nodded into any de-
sired form. 1t is soluble in acetate Of
amyl, forming a useful, quick-drying
varnish. 1t is manufactured in a vari-
ETY. of forms. limitations of tortoise
shell, amber and malachite are pro-
duced which often defy detection. The
sheet imitation of ivory is used in pho
Biography a basis for positives. A
most interesting variety of cellu1oid is
the transparent kind, which is manu-
featured into sheets one-one hundredth
of an inch in thickness and which has
a surface like glass. 1t is clear and I'M
affected by moisture, and is invaluable
to the photographer. The celluloid
sheets are manufactured in the follow
ing way: pile of pure white paper is
converted into nitrOcellulose by the ac-
ton of nitric and sulphuric acids.
After being freed from the acids by
washing, it is treated with wood spirit
and camphor, and a jelly-like block is
produced, which is subjected for several
weeks to great pressure. The block,
from which most of the spirit is evapo-
rated, is put into sort of planning ma
chine and cut into shavings of the
thickness of the film required, each
shaving or sheet of film, which measures
60X20 inches, is hung up to dry for a
period of three months, in order to
thoroughly season it and prevent any
Interchange. Each sheet is then taken
and rolled under great pressure be-
tween heated metal plates to obliterate
the marks of the cutting knife, which
becomes visible at any time afterward,
when the celluloid is moistened with
alcohol. The metal plates are polished
or grained, according to the surface re-
quired, the polished giving the smooth
film and the grained the matted sur
face. Both kinds are used. Some
makers of negative films coat the
matte film, leaving the matte surface
at the back. This plan is very good for
retouching, but the negatives take
longer to print, and the matte surface
is very liable to become scratched. The
gelatine emulsion is spread over the
sheets by means of special appliances,
which produce film of gelatino-br bro
mide of silver of great uniformity. The
emulsion is the same as that used in
the preparation of dry plates, and the
film when dry is precisely the same as
a glass plate, except that the support is
celluloid instead of glass. The i'm
mense advantage of celluloid films 60
the photographer arises from their
lightness and portability; dozen half
plate films weigh about four ounces:
the same number of glass plates would
average three pounds, while in thick
ness one gross of films will be four
inches against the fourteen inches OF a
gross of glass plates. Another gr.at
advantage is that there is no fear of
breakage, and Furthermore, halat! On
which is so common with glass plat /; is
almost entirely obviated by the us OF
flms.-N. Y. Times.