Page 23 - VMM_dec1951

Commercial Film Processing
By A. HALSEY.
Mr. Halsey was with the Technical Department of the J. Arthur Rank Organisa-
tion at Denham Studios Laboratories, England, where he was maiJ.Iy'lresponsible for
the development of the film, "Great Expectations," from the original camera
negatives to the final exhibition prints. It must be remembered that all com-
mercial film is made negative/positive (not reversal), and that the studios do
their own monochrome processing. Colour film is not done by Denham Laboratories,
but by the firm whose process is used, such as Technicolour.
Mr. Halsey is not connected' with the film industry in Australia, although he
was engaged in this industry in East Africa after leaving England prior to coming
to Australia.
PART II.
Changing Types of Film. the developing, ac id stc•p, rinse, fix,
To change from one make of film to rinse and drying sections.
another-say, from Kodak to llford- "Gamma Strips."
the blank film leader is threaded into the A "gamma strip" or control strip is a
machine, and the word is then phone:J short length of film which has been pre-
down to the chemists. The next film is exposed to a known degree, and is spliced
loaded ready for the chemicals to come, in at least every 2000 ft. to ensure th;;t
and the complete change of chemicals development is being carried through
takes about 15 minutes. In this period correctly. This strip of film is always
all chambers are emptie:i, flushed w;th cut from the make of film being used,
water under high pressure, checked with and may be read on a sensitometer,
I itmus paper to see if any traces of che- giving exposu re time, etc., any defects
mical remain in the flushing water, and, being known immediately and corrected.
when this paper is clear, the new chemi- A control staff is responsible for th ,~
ca l is pumped in and word phoned up ~o checking of each gamma .
the operators that it is now O.K. to com -
Lighting.
mence operations with th8 new film.
The operator at each end of the
Rate of Film Travel. machine works in a "safe" light accord-
The complete machine is driven from ing to his work. There are lights at
a large dynamo th rough a belt drive and
each end, which throw directional beams
a main shaft through bevel gears to the
on to the part where the operator works.
actual d ri ven sprockets in the chambers. At the threading end there is a posi-
The spee:J is controlle:J by a gear lever
tive .03 controlled light, covered by a
on a dial, which is measured in minute> filter according to the type of film being
- maximum speed, l minute, down to
used-negative or positive. At the take-
minimum speed, l 5 minutes, graded up end it is merely a controlled white
i·hrough -1- and -l- minutes.
light, used against cream walls. Ther<.
Four to four and a half minutes is the is no partition or screen between, the
normal setting, and this is the time
whole machine being visible from either
taken for development to be completed
end.
-through the three developing cham-
bers-or about 20 to 2 5 m1nutes through (Continued next page)
VICTORIAN MOVIE MAKERS e DECEMBER, 1951. 23