How does viscosity affect the quality of the print piece?

Answered by Clarence Penge, Product Manager, Heidelberg USA

What affects the viscosity of the dampening solution? How does this affect the print quality?

First let's look at viscosity and what it means. Viscosity describes the property of a substance to flow. The viscosity of the dampening solution changes because the water has more energy as the temperature increases. More energy means the molecules can move around faster. That being said, the easier it is to stir something, the lower its viscosity.

To answer your questions, the temperature affects the viscosity. A change in viscosity is usually most noticeable at the metering roller nip. Fountain solution that has temperature variations will affect how it is metered by changing the water film thickness. This has a direct affect on consistent print quality. By controlling the temperature of dampening solution we can better control the feed rate of solution to the plate and control ink tinting.

In addition, the temperature of the ink train will have a huge affect on the ink viscosity. A general rule would be for every 10 degrees of change in temperature of the ink train the viscosity will reduce by 50 percent. This can have a drastic affect on print quality.
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