Single-Color Press

A single-color press is a printing system composed of one complete printing unit. This unit includes its own inking and dampening systems, a feeder, a sheet transfer system, and a delivery mechanism. As shown in Figure 3-1, this configuration typically prints one color per press pass. Some models allow for modification of the inking system using ink fountain and roller dividers, enabling the simultaneous printing of two or more widely separated colors from the same plate.

True multicolor printing, which involves applying two or more colors—often overprinting one atop another—is also achievable on a single-color press. This process requires feeding each sheet through the press multiple times, once for each color. After each pass, the printing plate is removed and the inking system is thoroughly cleaned. A new plate is then mounted, and the system is filled with the next color ink. The sheet is run through again after the previously printed ink has dried. This method relies on dry trapping, where a dry ink film accepts a subsequent wet ink film, which then dries through oxidation polymerization.

The printing unit in a single-color sheetfed press is often referred to as an "open unit." Its plate, blanket, and impression cylinders are typically arranged in a near right-angle configuration (Figure 3-1). This design offers three primary advantages:

. It reduces the overall height of the press.
. It facilitates easier feeding of paper into the impression cylinder grippers.
. It allows all three cylinders to be disengaged from each other through movement of only the blanket cylinder.

As printing technology evolves, the fundamental principles of single-color presses remain relevant. These presses continue to serve specialized applications where cost-effectiveness and simplicity are paramount. In an industry increasingly focused on automation and sustainable practices, the efficiency of such established machinery provides a valuable counterpoint to fully digital workflows.