method to find the correct exposure time for the various colors. Once
you find the time for the various colors, note the time for future
The heat produced by the light source causes some expansion or shrinkage
of the image. To minimize these effects, always run diazo foils in the
same direction in the machine. When the machine has finished exposing
the foil, it may eject the foil and the master or just the master,
depending on the type of machine you have. If the machine ejects only
(2) Developing the foil. After you have exposed the foil and the
master, and the machine ejects the master and foil, feed only the diazo
key to the success of the process is remembering that exposure time in
the printing section is critical and time in the developing section is
not. You must leave the foil in the developing section long enough to
obtain maximum density and full color. You can remove it from the
ammonia vapors any time after reaching that point.
f. Mounting the Diazo Foils. Mounting the foil adds durability and
ease in handling the viewgraph. You can use commerciallymanufactured
cardboard or plastic frames or make your own. If you decide to
construct the frames, use an opaque material such as heavy cardboard,
heavy paper, or even a file folder, and cut the aperture to size (7 1/2
by 9 1/2 inches).
Whether you use a commercial or locallyconstructed frame, you mount the
foil using the same technique. Center the image on the foil in the
aperture opening on the back side of the frame, and use masking or
plastic tape on all four sides of the foil to secure it to the frame.
You cannot use cellophane tape to secure the foil because it dries up
and becomes brittle with age. Mounting and taping the foil to the back
of the frame produces a professionallooking viewgraph, assures a flat
The following discussion of a photostatic camera uses a Visual
Graphics POS 1 system, model 320.
The Photostatic Camera (figure 27).
You can use this camera to produce enlarged or reduced copies of camera
ready and tone illustrations.
a. Preparing the Camera. When preparing to make copies with this
camera, you must ensure the chemicals in the developing section are at
the required level and usable.