Testing Services for the paper, nonwovens, packaging, and consumer products industries.

Have questions? Give us a call 920-749-3040

TAPPI T 815 Slide angle COF






Coefficient of static friction (slide angle) of packaging
and packaging materials (including shipping sack
papers, corrugated and solid fiberboard) (inclined
plane method)


The TAPPI T 815 Slide angle coefficient of friction method determines the coefficient of static friction of most packaging materials by measuring the angle at which one test surface begins to slide against another inclined surface as the incline is increased at a constant and prescribed rate. The test is frequently referred to as slide angle. The coefficient of friction is numerically equivalent to the tangent of that angle. TAPPI T 549 describes a horizontal method for determining static and kinetic friction but is intended for application to printing and writing papers and the procedures are somewhat different.


The coefficient of friction of packaging materials indicates how packages made from that material will perform in many critical applications. A high coefficient of one surface of paper or paperboard (containerboard) to itself means that containers having that surface will tend to resist sliding in unit loads. A low coefficient may indicate potential problems with the packages slipping from the load.

The coefficient of static friction test is empirical. It describes the condition of that surface at the moment of test. This may or may not relate to the condition of that surface in use. Its condition will depend upon the historical treatment of the surface, especially if frictionizing materials have been used to treat the surface. These materials may be rubbed off in handling downstream. For surfaces treated with frictionizing agents, experience has shown that variability is significantly reduced after the third slide. Coefficient of friction is also significantly affected by contamination with very small amounts of materials which lower the friction such as waxes and other oily materials. As with surfaces treated with frictionizing agents, coefficient of friction test results on surfaces containing waxes or other oily materials also show reduced variability when preliminary conditioning in the form of slides are made before the results are recorded. Where the surfaces are known to have been treated with a frictionizing agent or suspected to contain wax or oily materials or when the previous history of the packaging material is unknown, test results are not recorded until the third slide. When it is known that the packaging materials being tested are untreated, test results may be recorded on the first slide with little or no loss in accuracy.


IPS tests Side A to Side A/ MD to CD unless a different orientation is requested.  Customer needs to designate “Side A.”


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