This practice is used for the preparation of test specimens for the internal tearing resistance of paper, board, and related materials when a force is applied perpendicular to the machine direction. Materials whose structures are highly directional cannot be properly tested in their cross direction according to TAPPI T 414 Internal Testing Resistance of Paper, because, as a rule, the tear turns toward the machine direction as it proceeds. Consequently, it is usually impossible to make a test tear of such a material truly in the cross direction. This method has been devised to permit the tear to proceed as it will, but more or less limits the extent of the tear to the prescribed 43 mm.
This test is a measure of the force required to continue a tear after it has been started. It does not necessarily bear any relationship to the force required to start a tear, for example, at the handle of a paperboard card.
