Waterless printing
[4] Waterless offset presses do not use a dampening solution to keep the plate's non-image areas free of ink.
A more common design includes a dampening system to allow the press to function conventionally when required.
This temperature distinction is achieved by running chilled water through tubing in hollow cores of two or more vibrating rollers which are found inside ink trains on printing presses.
When a job needs to be run again, the plate can be rehung on the press, and although the register must be created manually, a portion of the preparation is simplified, since the ink-key profiles can have been saved and reloaded.
Several problems were encountered both in the development of suitable inks for this process and more importantly, in the durability of the driography plate.
In 1972, Toray Industries, a large Japanese company specializing in synthetic materials development and manufacturing, purchased the patents for the driography product from 3M.
Toray's experience in working with synthetic materials and advanced polymer compounds allowed them to improve on the original product design.
Cooperative efforts from press, ink and paper manufacturers helped to support the product, and the overall market acceptance was very good.
The first North American demonstration of the waterless process was at Print '80, and with the introduction of the negative (TAN) type plate in 1982 this market could be seriously pursued.
Simple additions can be made to the water-less plate by scratching or scribing the silicone surface to expose the ink-receptive layers beneath.
The theory behind waterless printing is that the silicone material which makes up the non-image area of the plate has a very low surface energy.
Removing water from the offset process results in a loss of cooling effect on the surface of the plate.
Almost all sheet-fed press manufacturers offer hollow core ink vibrators which can then accept the after-market temperature control systems.
The function of the temperature control system is to circulate enough coolant through the roller train to carry away the heat that is generated by the mechanical actions in the printing unit.
This type of system is not designed to chill or refrigerate the inker, but merely to maintain its temperature at a constant throughout the press run.
