Q. We printed the body of a book using heatset web and the cover using sheetfed. About a week after the book was assembled, either the body grew or the covers became smaller: Why?
A. When printing heatset web, the dryer reduces the moisture content to almost zero percent. This causes the paper to shrink to its minimum dimensions. As it reconditions, the paper will grow perpendicularly to the gran (cellulose fiber grows in width not length). The paper should be allowed to recondition before binding or additional trimming will be necessary later.

Q. Why can't we produce consisten color from one run to another?
A. There are a variety of reasons. One probleem could be that density and dot gain has changed from the first run to the second. To check for this, take a densitometer and measure the solid ink density of the color bar. If the density is the same as the first run, check the dot gain at the mid-tone dot. The dot gain should be the same as on the previous run and also within 3% over the cyan, magenta and yellow to ensure gray balance. Any increase of decrease in dot gain range over 3% will cause a color shift visible to the human eye.

Q. Why does our magenta ink change hue and lose gloss after heatset drying?
A. Some pigments used in magenta ink will darken when heated. This could explain the change in color. The loss of gloss could also be caused by excessive penetration of the ink vehicle resulting in loss of gloss. We recomment using a more heat resistant pigment and reducing drying temperature to just enough to dry the ink (do not overdry).

Color Theory
Did you know that printing inks absorb and reflect the visible color wavelength? Color theory tells us that cyan ink absorbs the red color wavelength, magenta ink absorbs the green color wavelength and yellow ink absorbs the blue color wavelength.