Double Coating Wet on Wet with the Metering Size Press, 1996 Metered Size Press Forum Proceedings

Gunnar Engström

STFI

Veronique Morin

Domaine Universitaire

By installing a turning roll in the MSP (Metering Size Press) and modifying the web run, it is possible to double coat wet on wet with that unit - pre-coating with the MSP and the top coating with the blade. This coating procedure has been compared with conventional coating with the MSP and with coating with blade, with respect to “orange peel pattern” and contour coating, in a pilot coating trial. Double coating wet on wet with the MSP was found to combine the advantages of conventional coating with the MSP and with the blade - a contour coating without “orange peel pattern”. An analysis of the process of forming the coating layer, suggested that the base paper was more compressed when coating with the MSP, especially when double coating wet on wet, than when coating with the blade. The high compression led to a smooth base paper during the process of forming, and thus to a coating layer of uniform mass distribution on the fibre floc scale, i.e. to a contour coating. Key words: Coated papers, blade coating, roll coating, base papers, coating layer, forming, compression