METHOD AND APPARATUS FOR CONDITIONING A DAMPENING SOLUTION FOR HARDNESS CONTROL

摘要

A method and an apparatus for conditioning a dampening solution of a wet offset printing machine, include keeping constant or changing the hardness of the dampening solution added to a container during processing of a print job. The hardness of the dampening solution is determined by measuring the conductivity of the dampening solution and is converted into a hardness value according to a determined formula-based or table-based relationship between the hardness and the conductivity of the dampening solution. The change of the hardness of the dampening solution is compensated for during printing by replacing used or withdrawn dampening solution with dampening solution that has a lower or higher hardness, wherein the amount and/or the degree of hardness of the supplied dampening solution having lower or higher hardness is determined from the conductivity measurements and the formula-based or table-based relationship.