We offer 2 particularly handy procedures for determining this for the decisive property values of the adhesion .
Basically, the procedure according to ISO 8296 applies:
A film of specified liquid is applied to the surface whose status can be assessed after precisely 2 seconds.
Below is a trial with test inks of the value 46 and 48 mN/m:
[Determining the surface tension per tint line with BOPP, here the result is ≥46 mN/m]
If the film stands still for 2 seconds, the surface tension at least corresponds to the value assigned to the liquid.
If the film contracts to drops or lines during these 2 seconds, then the surface tension is below the value specified for the liquid.
Our test pens are ideal for a rough determination of the treatment status of e.g. BOPP film.
A quick stroke and it is quickly established whether the material is already pretreated.