Details:
Summary:
In the field of office duplication the planographic offset process possesses great flexibility and produces a superior copy but requires a somewhat more highly skilled operator than do other methods. A means of automatically maintaining the ink-water balance on an offset duplicator would greatly simplify the operation and much work has been done in an effort to accomplish this by using ink-fountain solution emulsions in the place of ink, but this has not been too successful. Another way of accomplishing this objective has just recently been achieved. Ink and fountain solution are fed to the form through the same train of rollers from two separate rate fountains. By this method, the balance is automatically maintained over a wide range of master materials, ink coverage and temperature-humidity variations. All of the rollers in the train are covered with ink but there is no apparent emulsification. It would appear that the water is present in a thin continuous film on the ink film and when the form roller contacts an imaged area on the form the water is forced away and ink deposited, but when the form roller contacts an un-imaged area the surface is kept free of ink by the deposition of a film of water.