People's voice. [volume] (Wellington, Sumner County, Kansas) 1890-1917, 1893-05-19
CELlULOIO FILMS.
Some Interesting Information Concerning
Their Manufacture.

Their Manufacture.
Celluloid, which is comparatively o
new product, dating back only to 1863,
has come to be of immense Importance
in the arts. 1t is hard, durable sub.
stance, almost entirely unaffected by
acids and alkalies, 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 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 as basis for positives. a
most interesting variety of celluloid is
the transparent kind, which is manu-.
featured into sheets one-one hundredth
of an inch in thickness and which has
surface like glass. 1t is clear and un.
affected by moisture, and is invaluable
to the photographer. The celluloid
sheets are manufactured in the follow.
ing way: A 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 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 a sort of planning ma.
chine and cut into shavings of the
thickness of the film required, each
shavingor sheet of film, which measures
6Ox2O 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 fol-
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-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 il
celluloid instead of glass The i'm
mense advantage of celluloid films to
the photographer arises from theil
lightness and portability; dozen half
plate films weigh about four ounces
the same number of glass plates woulG
average three pounds, while in thick
ness one gross Of films will be fow
inches against the fourteen inches of 2
gross of glass plates Another great
advantage is that there is no fear
breakage, and Furthermore, halation
which is so common with glass plate, il
almost entirely obviated by the use o
films.-N y. Times.