film, continue developing for 3 or 4
transmission will be piece-by-piece, and states
minutes. Total development time is
the number of pieces.
b. In establishing desired contrast range and
about 5 minutes at 70 F. Place the
gain setting for the transmissions, the transmitting
film in the middle tray for 5 seconds;
then place it in the hypo tray.
operator uses the phasing ring and the phasing
spot to send maximum and minimum signal levels.
(b) After all cloudy white portions of the
The transmitting operator does not use the darkest
film have cleared, lights may be turned
and lightest portions of the picture. This would
on for a few minutes. Leave the film
cause each piece of the complete picture to be re-
in the hypo for at least 15 minutes,
corded with different over-all densities.
then wash it for at least 15 minutes in
c. Once the transmitting GAIN and CON-
running water. After the film has
TRAST controls and the receiving GAIN control
been washed, hang it up to dry; use
are set correctly, they are not changed until the
last of the piece-by-piece copy has been received.
Caution: When handling film, be
The receiving drum must be rephased to the trans-
careful to avoid getting finger marks,
mitting drum before the start of each picture.
scratches, or dust on the emulsion.
Keep wash water and tray solutions as
32. Photographic Processing
near the same temperature as possible.
a. Developer and Hypo Solutions. Mix devel-
Never use warm water to wash film; it
oper and hypo solutions according to instructions
removes the emulsion from the film
on the containers of powder. Mix developer DK-
60A for film or developer D-72 for photographic
Note. For black and white copy such as
paper. The same type of hypo is used for fixing
maps or messages, use developer D-72 mixed
both film and paper.
1 to 1 instead of DK-60A. This will reduce
b. Darkroom Operations. Keep all lights except
the developing time. If rushed, fixing and
washing time can be reduced if it is not neces-
the safelight turned off until the photographic
sary to preserve the film. The film must be
copy has been fixed in hypo. Arrange three trays
clear before it is removed from the hypo.
beside the sink so that they are lighted by the safe-
Use of D-72 solution is not recommended for
light. Put developer in the left-hand tray, clean
photographic work requiring detail in high-
water in the middle tray, and hypo in the right-
lights and shadows.
hand tray. Be sure that there is enough solution
(2) Positive (paper). Use one part of D-72
(at least inch) in each tray to cover the copy
solution mixed with two parts of water
for developer. Be sure the temperature
(1) Negative (film). Use DK-60A solution,
of the developer is between 60 and 80 F.
full strength, for developer. Check the
(a) Place the paper in the developing tray
temperature of the developer with the
and watch the picture begin, to form.
thermometer. It must be between 60
When the desired density has been
F. and 80 F. for satisfactory results.
obtained (after 1 minutes), remove
Caution: Development will be slowed
the picture from the developer and
b y temperatures below 70 F. and
place it in the wash water in the middle
accelerated by temperatures above 70 F.
For consistent results, temperature of
(b) After about 5 seconds, remove the pic-
developers should be maintained at 68
ture from the washing tray and im-
F. by use of heat or ice. Immersing
merse it in the hypo. The lights
developer tray in another large tray of
may be turned on after the paper has
water at proper temperature will hold
been in the hypo for about a minute.
for a sufficient time to permit develop-
Leave the paper in the hypo for at
ment of several negatives.
least 10 minutes, then wash it in
(a) Immerse the exposed film in the
running water for 15 minutes.
d e v e l o p e r tray. Agitate the solution.
Watch the film as the picture begins to
(c) If Royal Bromide paper is used, place
form. After detail is noticed in the
the paper face down on a ferrotype
light portions of the lighter side of the
plate and force out the excess water