Figure 2-7. Diazo foil with slip sheet
(1) Run this assembly through the diazo machine. Ensure that your film develops fully.
This helps keep the image from fading, or the background from yellowing. The speed of travel through
the machine varies with color of the film. You may have to pass the film through the developing step
several times to ensure full development.
(2) Determining exposure time is generally a result of a trial-and-error process. Overexposure
results in the image being weak and faint in color. Underexposure will show a background. Once you
obtain the correct exposure time, make a note of it and post it near your machine.
(3) The heat of the light source may cause shrinkage or expansion.
To minimize this
distortion, you should run all of your foils in the same direction.
c. Developing. After you expose the master and foil to the ultraviolet light of the diazo
machine, the machine feeds the foil into the developing section.
(1) While exposure time is critical, development time is not. You must develop the film long
enough to obtain maximum color, but you may remove it anytime thereafter.
(2) If you make a mistake, or an unwanted mark appears on your produced film, throw it
away. Correct the master, or clean the diazo machine, and run another copy. Do not attempt to scratch
away mistakes from the film. Scratches project as dark spots or lines on the screen.
d. Flash Exposure. You can produce highly saturated colors using maximum density diazo film.
(1) To create a variety of color densities, you can "flash" expose your film by exposing it to a
light source. When you flash a film, some of the emulsion burns off. When you develop this film, the
color density is somewhat less.