Printing & Design Tips: OCTOBER 2007, #75

Waterless Offset, A.K.A. Dryography

Conventional offset printing is based on the chemical properties of oil and water. In short, they don’t mix. Therefore, with a little ingenuity, even on a flat surface like an offset printing plate, you can designate image areas that accept ink (and transfer the ink to a blanket and then to printing paper) and non-image areas that repel ink. You do this by carefully maintaining a precise ink/water balance on press.

This is all well and good, but it presents some problems. For instance, the water can streak the ink, and the water limits the line screen you can use to 175 to 200 lpi (image detail is limited).

An offshoot of conventional offset, called waterless offset or dryography, eliminates water from the chemical equation. Actually, it turns the printing process from a chemical balancing act (ink vs. water) to a mechanical process that can be more precisely controlled.

Because of this, press operators can offer the following benefits:

  • Brighter colors that are more saturated and vibrant.
  • Halftone line screens upwards of 300 lpi, that allow for consummate detail in the photographs, smooth blends, fine tints, and a dot pattern almost invisible to the naked eye.
  • Printing devoid of water spots.
  • More environmentally-friendly printing, since there’s no toxic fountain solution maintaining the ink/water balance and less paper waste since make-readies are quicker and more accurate.
  • The ability to print thicker ink-films with less dot gain (allowing for more saturated colors and greater color control).
  • Quicker drying times.

Basically, waterless printing is a winning proposition. According to the Waterless Printing Association, overall waterless printing costs are comparable to those for traditional offset. Although waterless plates and inks cost more than conventional supplies, make-readies take less time, and there is less waste. Therefore, when a printer dedicates a press exclusively to waterless offset, the lowered materials and labor costs offset any other increased costs.

However, this technology is very new and most printers probably don’t have it yet, so you wouldn’t use it for most print jobs. You might want to use it for a coffee-table art book that has to be perfect (that is, with images requiring superior tonal range and detail). Choosing waterless offset would require you to do a little searching for a vendor offering this technology.

But what is waterless offset, really, on a technical level?

Waterless offset uses plates and ink, like traditional offset lithography, but it employs no water, no fountain solution to keep ink on the image areas and away from everything else. To do this, waterless printers rely on special plates that are aluminum backed and coated with a photosensitive material and silicone. When these plates are exposed with a laser and then processed, the silicone rubber falls away from the image areas, leaving the aluminum base. Areas not exposed to the laser retain the silicone coating. In addition, the image areas are slightly recessed. (Therefore, waterless printing is really less of a planographic process like conventional offset and more of a mechanical process like the intaglio printing method called gravure.) Ink avoids the silicone and collects in the slightly recessed image areas and then is transferred to the blanket and from the blanket to the paper (just like conventional offset).

One variable that must be carefully controlled in waterless printing is temperature. On a conventional press, the fountain solution (usually composed of water and alcohol) is usually chilled, and this keeps the heat level on press under control. Without water, the process heats up the ink too quickly. If the ink gets too hot, it will become less viscous and may adhere to the silicone. Therefore, temperature must be regulated, and special inks must be used that are formulated to operate optimally within the temperature range of the specific press.

In general, waterless plates can be used for press runs between 10,000 and 600,000 images, depending on the plate manufacturer. It’s worth mentioning also that conventional presses can be retrofitted for this technique.

[Steven Waxman is a printing consultant. He teaches corporations how to save money buying printing, brokers printing services, and teaches prepress techniques. Steven has been in the printing industry for thirty-three years working as a writer, editor, print buyer, photographer, graphic designer, art director, and production manager.]