The offset printing process at minuteman is a very interesting. Offset lithography operates on a simple principle: ink and water don’t mix. Image information (art and text) is printed on plates which are dampened by water and ink by rollers on the press. The oil-based ink adheres to the image area, the water to the non-image area. The inked area is then transferred to a rubber cylinder or “blanket” and then onto the paper as it passes around the blanket. The process is called “offset” since the image doesn’t go directly from the plates to the paper, but is offset or transferred to another surface as an intermediary.

 

What’s involved in setting up an offset printing run?

To start a press run, the imaged plates are clamped onto the plate cylinders and the ink settings are adjusted for the density of ink needed for the particular run. The press operator then runs a batch of initial sheets through the press at low speed and carefully checks registration (alignment) of the colors and the ink/water balance to ensure full and steady ink flow for accurate color reproduction. The operator can adjust the plate positions and ink density while the press is running at low speed. This set up process is called a “make ready,” where highly-skilled operators prepare the press for perfect offset printing.