< Zurück zur Übersicht

The gelbo flex test according to ASTM F 392

Innoform Tested Siegel

Innoform Testservice frequently receives requests to test the mechanical strength of flexible (barrier) materials. These materials play a crucial role in many applications, from food packaging to technical protective films. A proven method for testing the mechanical strength of these materials is the gelbo flex test in accordance with ASTM F 392, which focuses in particular on the crease and buckling resistance of barrier materials such as film or paper laminates.

What is the gelbo flex test?

The gelbo flex test simulates the stresses to which flexible films are exposed during use. A film sample is stretched onto two rings in the shape of a tube and exposed to repeated pressure and squeezing movements. The intensity and frequency of these movements can be varied to simulate different application scenarios. When performing the test, a distinction is made between two main types, complete and partial twisting. These different methods make it possible to accurately simulate the specific requirements of different applications.

After loading: testing the samples

After the mechanical stress caused by the yellow flex test, the film samples can be further analysed in two ways:

Optical examination for pinholes: In this case, the sample is checked for small holes or weak points that may have been caused by the mechanical stress. This can be done either with the aid of a light table or a special test liquid. These pinholes may significantly affect the barrier properties. 2. permeation test: Using this method, the barrier effect of the stressed sample is compared with that of an untreated sample. This shows the extent to which the mechanical load influences the film’s ability to retain gases or water vapour.

Why is the gelbo flex test important?

In practice, high demands are placed on flexible materials. The yellow flex test offers a standardised method for evaluating the mechanical strength of these materials under realistic conditions. This enables manufacturers and users to ensure the quality and reliability of their products.


Innoform Testservice is your competent partner for testing the mechanical strength of flexible materials. With the gelbo flex test in accordance with ASTM F 392, we offer you a reliable method for testing and optimising the strength and barrier properties of your materials. Trust in our expertise and experience to ensure the quality of your products. www.innoform-testservice.de

Video Innoform Testservice