Dampening Solutions in Offset Printing – Part 2

Posted: October 22, 2017 in Color, Color Management, Dampening solution in offset industry, PH, Standardisation
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The popular “Heidelberg Learning tips” inputs on Dampening solutions in offset printing is rendered below for the benefit of readers.  This is second part of the series.

3. Water Hardness

The proportion of lime in the water can cause problems during printing, for example:

  • The inking rollers run blank (calcification)
  • Deposits on the rubber blanket
  • Impact on the pH-Balance
  • Fluctuation in the pH-Balance

The proportion of chloride, sulphate, or nitrate is too high, which in addition leads to corrosion. The overall hardness of the water may be measured simply by using test strips. Dip the hardness-strip briefly (1 second) into the water, then read the results after two minutes.

In order to ensure that the dampening solution preparation possesses the ideal degree of hardness, the principle of reverse osmosis for water desalinisation is used. In the process, the water is pressed against a membrane.

Water treated like this, emerges with a very low residual salt content. Subsequently, this osmosis water is reconditioned with salts, until it reaches a degree of hardness ranging from 8° dH to 12° dH.

4. pH-Balance

“pH” is derived from the Latin (Potentia Hydrogenii) and represents a logarithmic description of the concentrations of hydrogen ions. In other words, the pH-Balance is a measure used to determine the acid or alkaline content of aqueous solutions.

What type of acid or base is involved cannot be determined. A liquid with a pH-Balance of 5 has 10 times more acid than a liquid with a pHBalance of 6. As a general rule, dampening solution additives are buffered, in order  for the most part  to neutralize external influences.

A pH-Balance measure does not tell us very much about the quality of the dampening solution. The measure only shows, whether an additive is present or not. Naturally, in order to determine the quality of the dampening solution, its conductivity should also be determined.

you can buy the pH Meter from Amazon, by clicking the above image.

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