Water absorbency of nonbibulous paperboard, Useful Method UM 596 (2015)
A standard test method used to determine the water absorbency of non-bibulous paperboard by measuring its water absorption rate, and it is suitable for paperboard 0.2 mm (0.008 in.) thick or thicker.
The test's purpose is to measure how quickly water is absorbed by paperboard that is not designed to be very absorbent, like paper intended for writing.