Patent attributes
A ventilation board is manufactured from a corrugated board comprising at least one depressed portion on both sides of the board in such a way that flutes of the corrugated layer between said depressed portions are exposed to form a plurality of passageways for passage of fluid across the board, in other words, from one side to the other side of the board. The depressed portion is formed by forming a cut on the surface of each side of the board in such a way that the cut penetrating from one side of the board passes through the corrugated layer of the corrugated board but does not pass through the other side of the corrugated board, and depressing the cuts in such a way that the flutes between the depressed portion get exposed in order to provide passageways for passage of the fluid across the board.
