eliminating the constant need to find the correct exposure setting.
The graphic on the master must not allow the ultraviolet light to pass
through or penetrate to the diazo film. Therefore, you must ensure the
entire image is opaque (will not allow light to pass through). To ensure
the graphic is opaque, use a good quality India ink when inking the
graphic. You cannot use regular pencils, transparent inks, or typewriter
ribbon to create opaque graphics or lettering on a diazo master.
Diazo developing methods
(2) Lettering height.
If you are preparing a master for a
viewgraph, ensure the lettering is the correct size for the viewgraph's
The distance the farthest viewer and the projector are
from the screen dictates the minimum size of the lettering used on the
viewgraph. If you were to calculate this mathematically, you would have
to consider the enlargement of the viewgraph on the screen, the average
vision of the audience (20/20), and perform a complicated math operation.