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TAPPI T 489 Stiffness






Bending resistance (stiffness) of paper and
paperboard (Taber-type tester in basic configuration)


TAPPI T 489 covers a procedure used to measure the resistance to bending of paper and paperboard. This test method is used to determine the bending moment required to deflect the free end of a 38 mm (1.5 in.) wide vertically clamped specimen 15° from its center line when the load is applied 50 mm (1.97 in.) away from the clamp. The resistance to bending is calculated from the bending moment.

TAPPI T 566 “Bending Resistance (Stiffness) of Paper (Taber-Type Tester in 0 to 10 Taber Stiffness Unit Configuration)” describes a modification of the instrument described in this test method for measurements in the 0 to 10 Taber stiffness range only, and which requires a smaller test specimen. The modified procedure may be recommended for papers which are low in grammage, highly flexible, or both.

Summary of test method

A test specimen of defined dimensions is bent through a specified angle using a specific testing instrument. The resulting bending moment is read from the instrument scale. The resistance to bending is calculated from the bending moment.


A physical characteristic of paperboard which differentiates it from paper is its greater flexural rigidity, commonly called stiffness. For most of its uses, the economic value of paperboard depends upon its bending resistance (stiffness), and because this property is closely related to the amount of fiber in the board and hence to its cost, a quantitative measurement is of considerable interest to both producer and user. Bending resistance (stiffness) of paper relates to a number of end use applications, including wrapping, printing, etc.



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IPS cannot sell or otherwise provide standards, specifications, or test procedures to third parties.