A right-reading (non-mirrored) image is etched onto the printing plate
Printing plates are mounted on plate cylinders of the press.
Paper is pulled off the stack by the feeder unit and fed into the press. Grippers hold the paper onto the impression cylinder.
Ink is distributed to the plate through several rubber or silicone-based
ink rollers. Fountain solution, the water and acid etching solution that prevents ink from sticking to non-image areas, is distributed through a chrome fountain roller.
Ink is transferred from the plate to the blanket cylinder which
is wrapped with a fabric-backed rubber blanket. The image on the blanket is now mirror-imaged.
The blanket cylinder and the impression cylinder meet and roll against
each other under high pressure and the reversed image transfers to the paper as a right-reading image.
The paper is released and fed to each successive ink unit, laying all
the colors on the paper, until it reaches the delivery unit and is stacked on a rolling pallet.
The most elusive task in printing color is controlling the many factors that affect how the ink actually gets to the paper. Cylinder pressure, blanket condition and packing, fountain acidity, powder usage, press speed and quality, ink density, and grade of stock used all affect the difficulty of printing the project. Of all these factors, ink density is the most difficult and time consuming factor for a press operator to control consistently. The Tobias IQ 200 (Scanning Densitometer) is an invaluable tool for controlling ink distribution and density on the press.