Abstract: A paper coating system is characterized by an upstream dip roll applicator that applies an excess layer of liquid coating material onto a surface of a paper web, and an improved downstream doctor assembly for metering and leveling the coating on the web. The doctor assembly includes a doctor blade having a tip extended against and across the web and a shear plate, upstream of the blade, having a surface extending across and defining a gap with the web. An elongate chamber defined between the shear plate and blade extends across the web, and excess coating removed from the web by the blade flows into the chamber. Coating is drained from and uniformly along a lower end of the chamber at a rate to maintain an eddy current pool of coating in an upper end of the chamber immediately upstream of the blade/web nip, but to prevent formation of a liquid seal in the gap.

Abstract: A paper coating system is characterized by an upstream dip roll applicator that applies an excess layer of liquid coating material onto a surface of a paper web, and an improved downstream doctor assembly for metering and leveling the coating on the web. The doctor assembly includes a doctor blade having a tip extended against and across the web and a shear plate, upstream of the blade, having a surfaces extending across and defining a gap with the web. An elongate chamber defined between the shear plate and blade extends across the web, and excess coating removed from the web by the blade flows into the chamber. Coating is drained from and uniformly along a lower end of the chamber at a rate to maintain an eddy current pool of coating in an upper end of the chamber immediately upstream of the blade/web nip, but to prevent formation of a liquid seal in the gap.