A Primer on a Different Type of Printing Process: Dryogrophy

7 08 2008

Most of the color printing that happens at commercial printers is through a process known as “offset printing.” Offset printing is based on the fact that oil and water don’t mix. This type of printing is a method during which an inked image is transferred, or “offset” from a plate to a rubber blanket, and then to a printing surface which accepts the ink and repels the water (for the non-image areas). This process has worked fairly well, but it does have a couple of problems: the water can smudge the ink and the water limits the amount of image detail.

So, to try to improve upon offset printing, an alternative method called waterless offset, or dryography was created. Dryography takes water out of the equation. Instead of it being a chemical process of ink versus water, dryography is a mechanical process that can be more easily controlled.

Benefits of dryography
Because dryography can control the color printing process better, you can get:
• Brighter colors
• Better halftone screens that produce greater detail in photos, blends and tints along with a dot pattern that can barely be seen by the naked eye
• No water spots
• Quicker drying times

How waterless offset works
Waterless offset uses ink on plates, just like offset printing, but it uses no water to keep the ink out of non-image areas. Waterless printers have special aluminum-backed plates that are coated with silicone and a photosensitive material. The plates are exposed with a laser and then processed, during which the silicone falls away from the image areas leaving the aluminum showing. The areas that aren’t exposed to the laser keep the silicone coating. Ink avoids the silicone and collects in slightly recessed image areas. Then the plate is pressed to the blanket and from the blanket to the paper (just like in offset printing).

And the cost?
Waterless printing costs basically the same as traditional offset printing. The waterless plates and inks cost more, but it takes less time for set-up and there is less ink and paper waste with dryography. Therefore, the printing company comes out even whether it uses waterless or offset printing. So you can get brighter colors, more detailed photos and a shorter drying time for the same amount of money.

Dryography is not in widespread use yet
The technology is still pretty new and most printers don’t use it yet. But it’s something to be on the lookout for. Currently, waterless printing is used mainly for art books that are comprised of images that need superior color range and detail.

The disadvantages of dryography
The temperature must be carefully monitored and controlled during waterless printing. In a traditional printing press, the water keeps the heat level of the press under control. When there’s no water, the process heats the ink quickly. When the ink gets too hot, it could stick to the silicone. So, the temperature must be monitored at all times. Also, special inks have to be used that can operate in this higher temperature range.




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