Physical properties testing for labels

Those labels must not wrinkle or bubble. They must be suitable for applying to the neck or centre of the bottle and sometimes they may even need to withstand the rigors of an ice-bucket.

Checking the physical properties of labelling is often done by checking their frictional and tensile properties.

Coefficient of Friction (COF) is a significant topic in the world of packaging and is an important property of all materials that run on packaging lines.

By definition, COF is a measure of slip, or how one surface moves across another.  Its importance lies in in how a substrate moves through and across print stations, conveyor belts, onto the container, or is released from a mandrel or loading after processing. 

Mecmesin - MultiTest with Coefficient of Friction application test rig/slide table

Types of coefficient of friction (COF) testing

There are two types of COF:

  • Static
    The force needed to begin movement
  • Kinetic
    The force required to maintain movement

COF is usually specified for a given process and can be adjusted by the printer with inks or varnishes as needed.