FIGURE NUMBER 11 - SEN5IT0METRIC CURVE - DIAZO NEGATIVE FILM 
Negative working diazo-sulfonate films differ from the positive 
working diazo films in that they are passive, and exposure to actinic 
light converts them to the active diazonium form. Once activated by 
exposure to U.V, or visual blue light, azo dye is coupled in areas of 
U.V. light exposure. The reaction is pH adjusted by passing through a 
warm moist chemical vapor, and the unexposed diazo salts are removed by 
re-exposure to strong actinic light. Figure 11 shows the sensitometrie 
curve for a laboratory experimental pilot coating of a new black image 
diazo negative film which is believed to be a technological break 
through, This film has a gamma of 1,0 and a density scale of 2,02, 
Past diazo negative films have required a wet water wash to remove 
unreacted chemicals for image permanency, and have produced orange, 
sepia, or maroon images only, 
FIGURE NUMBER 12 - VARIABLE CONTRAST RESPONSE OF DIAZO FILM 
Many continuous tone diazo positive films consist of two different 
contrast response diazo salts plus a U,V, absorbing chemical to control 
decomposition rates. It is therefore possible to change the contrast 
response of these films by selective filtration of the emission line 
spectra of a mercury vapor exposing light source. This figure shows 
how a single coating of black diazo positive film can be made to respond 
with different contrasts by selective filtration of the line emissions 
of a mercury vapor light source, 
4046 Angstrom line = Gamma of 2.50 Density Scale of 2,50 
3660 Angstrom Line = Gamma of 1,64 Density Scale of 2*39 
4358 Angstrom Line = Gamma of 1,33 Density Scale of 2,27 
FIGURE NUMBER 13 - THREE GENERATION DIAZO PRINTING 
Shown here is a three generation printing test, A 21 step 0,15 
density increment gray scale was exposed onto diazo negative working 
film. The negative film was then printed onto a medium contrast positive 
working diazo film to produce the second generation print. The second 
generation copy was then printed onto the medium contrast diazo positive 
film again to produce the third generation print. A useful Log E of 1,48 
was returned through this three generation printing. The formulation of 
the new longer exposure scale diazo negative and positive films will 
eventually extend the useful Log E through several generations of 
printing, 
A three generation printing test was conducted to determine the 
ability of a medium contrast diazo black image positive film to retain 
image resolution. Tests were made using a silver film original which 
resolved 400 lines/mm of a 5 to 1 aspect ratio triglyph bar and space 
pattern target with a low contrast (0.20 density difference). A mercury 
vapor lamp was used for the exposures. The following low contrast 
resolution was obtained for this test. These tests were conducted on a 
8" diameter drum type diazo printing machine.