Ring crush of paperboard (rigid support method)

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.