Applies to a wide range of papers and boards, but for some materials, such as multi-ply papers and boards, papers and boards with appreciable curl, some soft papers with grammage below about 40 g/m , the measured numerical value may not be strictly identical with the bending stiffness. It does not apply to corrugated boards.
ISO 5629:1983 history
2017ISO 5629:2017 Paper and board - Determination of bending stiffness - Resonance method
1983ISO 5629:1983 Paper and board; Determination of bending stiffness; Resonance method