Method and apparatus for preventing the curling of a composite material having a fluid permeable base and a fluid impermeable outer surface in a manufacturing operation wherein a continuous sheet of the composite material is moved in incremental amounts through a cutter-creaser apparatus to have carton blanks formed therein wherein the curling is prevented by forming a curtain of air under pressure to apply downwardly directed forces on the fluid impermeable surface during the incremental movement of the continuous sheet through the cutter-creaser apparatus and the forming of the carton blanks.