One problem with offset printing is that the ink is usually not sufficiently dry after printing, and therefore direct further processing/finishing of printed sheets is not possible.
In offset printing a sufficiently dry sheet that can be further processed is only achieved through special additional drying units integral to the machine. Hot-air and infrared drying are state-of-the-art; in particular, UV drying, in conjunction with special inks, makes it possible for the sheet to be dry when it arrives in the delivery or to be directly further-processed in line.
In sheet-fed offset insufficient drying is often compensated for by the application of powder in the delivery section so that undesirable quality-reducing ink set off in the pile is prevented, and furthermore rather quicker finishing is possible . Powdering is an additional operation bound up with costs, and it leads to certain areas of the press getting dirty, and therefore to extra cleaning work and possibly also quality-reducing effects (e.g., in print jobs with coating, or through the generally gloss-reducing effect of fine powder particles). A particular challenge facing ink manufacturers is the development of new ink systems to bring about speedier drying.
A number of proposals are under discussion, for example the development of water-based, quick-drying offset inks. The development of new drying equipment and drying processes is likewise just as great a challenge for the supply industry as it is for printing press manufacturers.