The job of dampening form rollers is to take up the fountain solution uniformly from the transfer or metering roller, transfer it to the printing form and provide a good ink-fountain solution emulsion. When a dampening film is taken up by a dampening form roller, the film is stretched, as the dampening form rollers runs much faster than the metering roller. Here, it is important that part of the fountain solution is emulsified in the ink. Thin negative lines and structures in the image are kept free of ink by the fountain solution emulsified in the ink which is released, when the emulsion separates under the pressure of the plate roller.