Process Color Printing On A One-color Press

Likewise, cyan is contaminated with about 25 percent magenta. That's why an overprint of 100 percent solid cyan and magenta doesn't produce the expected hue of blue but looks purple. Fortunately, yellow is very clean and pure.

When printing four-color on a two-color press, print those colors that are the least important on the first pass. These are obviously yellow and black. Yellow has very little contrast and is difficult to see alone. Viewing yellow ink on white paper through a blue filter, such as a Kodak Wratten #47, makes the yellow ink appear as black, not green. In fact, this is exactly the same filter that is inside PMT (photomultiplier tube) drum or CCD (charged coupled device) flatbed scanners, as well as densitometers. Being so difficult to see, yellow should be controlled with the use of a reflection densitometer.