scope:

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

This method was originally developed for paperboard between 0.28 mm (0.011 in.) and 0.61 mm (0.024 in.) thick. It may be used with higher variability for paperboard as thin as 0.18 mm (0.007 in.) and as thick as 0.76 mm (0.030 in.). A significant fraction of the paper in use in the industry now falls below the 0.28 mm (0.011 in.) value.

NOTE 1: Caution should be used when testing linerboard less or greater than the specified thickness as the results may be less reliable. Note in particular the increase in the R&R values in 10.3 as basis weight of the paper decreases. For papers thinner than 0.28 mm (0.011 in.), test values 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, 5).