Existing comment:
Offset Plates
The historic front pages offset plates on display at the National Press Club represent the most common, advanced method of printing newspapers. As a form of lithography, offset printing is distinguished from letter-press of relief printing represented by the earlier stereotype mats on display in the main lobby.
In offset lithography, a newspaper page is composed, assembled, and photographed full-size. The negative is exposed to light over a chemically-treated, light-sensitive metal plate. Wherever light strikes, a surface is created to which ink with adhere.
The prepared offset plate, wrapped around a press cylinder, is inked and then transfers, i.e. off-sets, the ink onto a rubber blanker, which prints the page.
Because it requires far less pressure than letter-press printing, offset reproduction allows for increased production speeds, improved reproduction of fine tones, and more efficient full-color printing. |