Abstract: An apparatus for treating the surfaces of a panel with irregular sides. Sealant is pressurized by applicator rolls acting on the top and bottom faces of the panel while sealant, deposited on the panel sides, is dispersed thereover by the side located spreader rolls. Side applicator rolls are stationed in series along each side of the moving panel with a first series of rolls each having an annular portion for pressuring sealant into the surfaces of the grooved side of the panel. Similarly the tongue side of the panel is sequentially treated by the rolls of a second series each having a circumferential recess within which is received the tongue of the remaining panel side. Additional rolls surface treat the panel faces. The side applicator rolls are biased into panel side engagement by spring assemblies which couple opposed side applicator rolls to one another to permit same to accommodate a moving panel with uniform pressure regardless of discrepancies in the panel path.