Ultrasonic testing of paper: how it relates to mechanical properties and tissue softness

One of the most useful tests for examining relative sheet quality changes is sonic propagation through and along sheets. Originally rediscovered for paper in the 1960’s, the technique is often underutilized and overlooked for paper applications in favor of mechanical measurements. A major selling point for ultrasonic measurements is that it is comparatively quick, requiring no particular sample test piece size and is non-destructive. These features are very useful in a testing laboratory allowing first pass screenings of sample sets which can be followed by standard mechanical testing to ascertain any differences that may be of interest to explore such as the effects if various pulp treatments to enhance properties.