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Summary:
The ink transfer process has been a subject of interest for many years. Walker and Fetsko created an equation for the process in 1955. According to theory the three parameters controlling the ink transfer are immobilization, splitting, and ink coverage (smoothness). Later, new equations have been developed, almost all based on the same theory. During recent years, some researchers have argued against the theory, because of correlation between the parameters. Also, some visual observations have created criticism against the theory. This study has concentrated on ink transfer in coldset offset printing using a rough uncoated newsprint surface. Some earlier results will be referred to also. During multi-colour printing the earlier printed inks are influenced by subsequent ink coverage such that the first printed ink can flow readily under the surface fibres. This is not common if only one colour is printed, but the situation seems to be very sensitive to the amount and viscosity of the inks printed.