Today's lithography is photo-offset lithography, an indirect printing
method.
The process transfers ink from the plate to an intermediate
rubber-blanketed cylinder that offsets the ink to the paper.
Figure 2-26 shows this process. Notice how the figure shows the plate
cylinder contacting the offset cylinder, then rotate to contact the
dampening rollers before the surface of the printing plate contacts the
inking rollers.
This ensures the nonprinting surfaces are damp and
reject the ink, the lithography principle.
Figure 2-26.
The basic offset lithography principle
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