Method for controlling warp in the manufacture of corrugated paperboard

In a method for the manufacture of corrugated paperboard sheets comprising the steps of forming a continuous composite paperboard web composed of a corrugated paper medium interposed between a top paper liner and a bottom paper liner and provided with a moisture-laden heat-setting adhesive material at the juxtaposed surfaces thereof, setting said adhesive material to firmly bond together said juxtaposed surfaces by heating said paperboard web to a temperature sufficiently high to effect vaporization of said moisture from said adhesive material, cutting the resulting bonded paperboard web into individual paperboard sheets, and collecting said paperboard sheets into stacks;

• the improvement whereby warp of said paperboard sheets may be effectively controlled comprising the step of applying to at least one side of said bonded paperboard web prior to its being cut into individual paperboard sheets and before it has cooled from its bonding temperature to a temperature below about 130.degree. F a quantity of moisture regulated so as to effect an adjustment of the relative moisture exchange rates of said top and bottom liners of said bonded paperboard web with the ambient atmosphere to the point which will result in a counterbalancing of the net effect of the warp-producing conditions developed within said bonded paperboard web prior to and during its bonding operation, the achievement of said counterbalance point being indicated by a consistent substantially flat condition of said paperboard sheets in said stacks.