Sensitivity of Representative Lithographic Plate Systems to the Mercury Arc Spectrum.

In view of the increased use of ultraviolet absorbing polyethylene terephthalate film bases and the introduction of pulsed xenon arc lamps which produce less usable short wavelength radiation than corresponding carbon arc lamps some knowledge of representative litho plate systems is desirable. A qualitative procedure for the determination of spectral sensitivity was employed by exposing the light-sensitive plates to a mercury arc spectrum in a quartz optics Littrow spectrograph. The exposed plates were then processed according to manufacturers instructions. Results of several litho plate systems processed in this manner are shown. These are compared to spectral absorption curves of solutions of the light-sensitive coatings.