The fountain solution for commercial web offset presses is different from press rotation printing, and is more different than offset offset printing. It requires that the fountain solution should be conducive to stable water and ink balance, the amount of water in the ink is small, the concentration of the ink is ensured, emulsification is reduced, and stable printing quality and rapid start-up of the machine are ensured even if the machine is operated for a long time. In the continuous water delivery system, the import fountain solution additive concentration ratio of 2% to 3%, IPA (isopropyl alcohol) ratio of 6% to 8%, the hardness of the solvent water used is 4 ° ~ 25 ° DH, PH value is controlled from 4.9 to 5.2 (according to the water hardness can be slightly adjusted), conductivity 800 ~ 1200μs/cm; the fountain solution used at the same time should make the ink roller does not retain calcium deposits, reduce the residual ink on the blanket And paper powder, to be effective in preventing foam and microbes.
When the pH of the fountain solution is too low. The dampening solution will react with the desiccant in the ink. The stronger the acidity of the dampening solution is, the slower the ink will be dried. When the pH value is too high, the IPA value is often too high and the ink film layer will lose its luster. It looks like the surface of the printed product is velvety and boring.