scope:

The ring crush test correlates with edgewise compression strength of paperboard (1,2).

This method is intended for paperboard between 0.28 mm (0.011 in.) and 0.61 mm (0.024 in.) thick. It may be used with less reliability for paperboard as thin as 0.18 mm (0.007 in.) and as thick as 0.76 mm (0.030 in.).

NOTE 1: Caution should be used when testing linerboard less or greater than the specified thickness as the results may be less reliable. For papers thinner than 0.28 mm (0.011 in.), test values may result from a combination of both buckling failure and pure compression. For papers thicker than specified, strain within the sample arising from bending the specimens into a cylinder may impact test results (3,4).