FINAT FTM 29 Scratch resistance

We perform testing in our laboratory according to FINAT FTM 29 to determine the scratch resistance of UV printing inks and coating layers on various printed substrates. The test is used to evaluate the mechanical resistance of cured ink films to defined scratching loads. It enables the assessment of whether printing inks and coatings can withstand mechanical stresses during converting, transport and end use while maintaining a high-quality appearance over time.

Application of FINAT FTM 29 Testing

The FINAT FTM 29 test is used to evaluate the scratch resistance of printed self-adhesive materials as well as other printed paper, film and composite substrates. It is particularly suitable for paper labels, film labels, BOPP, PE, PP, PET and PVC films, as well as other printed self-adhesive constructions and packaging materials. The method is primarily intended for UV-curable printing inks and UV coatings but can also be applied to water-based and solvent-based printing inks as well as protective coatings. 

The test provides valuable information on the degree of crosslinking and the quality of ink curing, as well as on the mechanical resistance of the printed image to scratching. It enables the assessment of whether printed materials can permanently withstand the mechanical stresses encountered during converting, transportation and end use.

Test Procedure and Details

According to FINAT FTM29, the surface of the printed test specimen is scratched using a sclerometer equipped with a tungsten carbide stylus under a defined spring force over a specified test distance. The applied force is increased stepwise until visible changes to the ink film occur. After each test step, the scratch mark is visually examined and, where necessary, assessed using a magnifying glass.

The evaluation distinguishes between simple deformation of the ink surface and actual removal of the ink layer. If ink removal occurs, it is further assessed whether only part of the ink film has been removed or whether the substrate has become visible. FINAT FTM 29 uses a three-level rating system for objective evaluation:

Level 1: Deformation of the ink surface without ink removal.

Level 2: Partial removal of the ink film without exposing the substrate.

Level 3: Complete removal of the ink film with the substrate becoming visible.

The target test result is Level 1 at the highest possible test force. The required spring force depends on the material being tested and must be established individually for each printing system, since both the hardness of the cured ink film and the stiffness of the substrate significantly influence the results. Flexible film materials, for example, may deform at lower forces than rigid substrates.

The method provides a reproducible means of evaluating scratch resistance both for repeat testing of identical printed products and for comparing different substrate and ink systems. For multicolour prints or combinations of different printing processes, the method can also reveal adhesion problems between individual ink layers. Printing inks containing silicone or wax additives can likewise be evaluated, since superficial lubricating or wax layers are displaced as the applied test force increases.

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