Dimensional Stability and the Influence of Conditions in the Printing Nip, 1996 International Printing & Graphic Arts Conference Proceedings

Göran Lindholm

The Institute for Media Technology

It is known that the configuration of the press affects the tendency for register deviations, but less is known about the effect of the conditions in the printing nips. It has been noticed during full-scale trials that the blanket can affect the register deviation when, for example an old blanket is replaced by a new one. Test printings have been made in a laboratory web offset press with a compressible and a non-compressible blanket and the widening has been evaluated by measuring the register deviation. The printing pressure was varied and the printings were performed both with and without dampening water. The results were sometimes very surprising. For example, the register deviation could be higher when printing without water than printing with water. The conclusion is that the widening of the paper not necessary is responsible for the register deviations. Therefore, paper widening cannot be evaluated by measuring the register deviation without having full control over other press parameters.