FINAT FTM 15 Surface tension

At our test laboratory, we perform testing according to FINAT FTM 15 to determine the wettability of corona-treated plastic films. The test is used to evaluate the surface energy of films and to assess their suitability for subsequent converting processes such as printing, coating, laminating and bonding. It allows verification that the surface treatment provides sufficient wettability to ensure reliable adhesion of printing inks, coatings, adhesives and other functional layers.

Application of Testing According to FTM 15

Testing according to FINAT FTM 15 is used to assess the wettability and surface activation of plastic films following corona, plasma or comparable surface treatment processes. It is particularly suitable for film materials based on polyethylene (PE), polypropylene (PP), polyester (PET) and other polymers used in the label, packaging, printing and coating industries.

The test provides valuable information on the quality of the surface treatment and supports the evaluation of film processability for subsequent printing, laminating and bonding operations. It also enables verification that the achieved level of surface activation meets the requirements of the intended application.

Test Procedure and Details

According to FINAT FTM15, the wettability of the film surface is determined using standardized test liquids with defined surface tensions. The test liquid is applied to the film surface and its wetting behaviour is visually evaluated within a specified period of time.

The highest surface tension at which the test liquid forms a continuous film and uniformly wets the surface is taken as a measure of the material's surface energy. The results are typically reported in mN/m (millinewtons per metre) or dyn/cm, allowing an objective comparison of differently treated films.

Complementary Test Methods for the Characterisation of Films and Labels

The characteristic values determined according to FINAT FTM 15 provide important information for evaluating the surface properties of films and labels. For a comprehensive characterisation, they are frequently combined with additional test methods.

The wettability of corona-treated plastic films is closely related to the adhesion of printing inks, varnishes, coatings and adhesives. Therefore, contact angle measurements and the determination of surface free energy according to DIN EN ISO 19403 are commonly used as complementary methods. This standard enables a precise assessment of surface activation and provides valuable information for the design and optimisation of printing, coating, laminating and bonding processes.

DIN EN 14370 can also be used as a complementary test method. It describes the determination of the surface tension of liquids and is particularly suitable for the characterisation of printing inks, varnishes, coating materials and similar liquid systems. The combination of both test methods enables a comprehensive evaluation of the interaction between liquids and solid surfaces and supports the development of reliable adhesion and wetting processes.

Please feel free to request this test or obtain information about our complete FINAT testing programme.