How do alkaline papers and dampening solutions behave and which reaction results?
While dampening solutions have a pH of 4.8 to 5.5, alkaline papers have a pH of 8 – 11. A reaction between these two cannot be avoided. The calcium carbonate in the paper is dissolved by the acidic dampening solution. The calcium salts can enrich in the circuit of the dampening solutions, and this enrichment can result in a series of troubles in printing for e.g. • Increase of the pH-value • Accumulations on the blanket The dissolved components of the coating mostly accumulate in the last printing unit. • Inking rollers running blank Salts that do not dissolve easily will build up in the pores of the inking rollers and render them hydrophilic. The water infiltrates the ink film, the ink will be displaced and the inking rollers will partly run without ink. The regeneration of blind inking rollers can only be achieved with specific washing agents. • Printing plates running blind Recommendations for the prevention of problems PH has a decisive effect on the dissolving speed of calcium car
