Dampening Fluid
Water-based chemical mixtures used in lithographic printing keep the non-image areas of the plate clean and receptive to water. Commonly called fountain solution, this fluid is continuously applied to the printing plate during operation to repel the oil-based offset ink. It prevents ink from adhering to the blank areas of the plate, ensuring sharp image transfer.
The liquid must maintain a precise pH and conductivity to function correctly without damaging the plate coating or emulsifying the ink. Its active formulation typically contains mild acids, buffers, gum arabic, and wetting agents.
Wetting Agent
Surfactants in the fluid lower its surface tension, allowing it to form a thin, continuous film over the plate. This thin film must resist the high forces generated in the nip between the plate and the dampening rollers. Proper surface tension prevents both dry-up and over-emulsification on the press.
Run Stability
Inadequate dosing of the concentrate leads to ink piling on the blanket, while excessive dosage causes the ink to bleed into the dampening system. Operators monitor the temperature of the system to control evaporation and preserve the viscosity of the fluid. Stable run conditions are impossible without regular monitoring of these fluid properties.
