Patent ID: 7175731

Claim:
A method of manufacturing tearable sheets of paper, each sheet of paper having fibres wherein each sheet of paper obtains a straight vertical tear edge and a stub when torn-off obtaining a step-like appearance, said method comprising the steps of punching via a hardmetal cutting line each sheet of paper transversely of the fibres of said sheet of paper from the first side of the sheet to a depth corresponding to a first portion of the thickness of the sheet; and punching via a hardmetal cutting line each sheet of paper transversely of the fibres of said sheet of paper from the second side of the sheet to a depth corresponding to a second portion of the thickness of said sheet; wherein the sum of said first thickness portion and said second thickness portion is smaller than the thickness of the sheet, and wherein the second punching operation is performed parallel with the first punching operation but displaced in a plane parallel with said first and said second sides of the sheet, said displacement being adapted for tear-off purposes.