Adhesion tests (tearing, gridding, evaluation of blistering rate, etc.)

Adhesion tests assess the resistance of a coating, paint, or protective film to separation from its substrate. These tests are essential for determining the adhesion quality , durability , and mechanical strength of a multilayer system. Performed using various standardized methods, they constitute a key performance indicator in the fields of materials, polymers, packaging, industrial paints, and functional coatings .

Principles and objectives of adhesion tests

Adhesion refers to the ability of a coating to remain fixed to a substrate despite the mechanical, thermal, or environmental stresses to which it is subjected. Poor adhesion can lead to delamination, cracking, blistering, or premature degradation of the material.

Adhesion tests allow us to:

• Measure the pull-off force between the coating and the substrate;
• Evaluate the film's resistance to tension, shear, or mechanical shocks;
• To qualify the quality of the application (paint, varnish, glue, polymer, metallization, etc.);
• Preventing failures during use or accelerated aging of products.

These tests are essential for quality control , research and development (R&D), as well as the validation of industrial coating or bonding processes.

Most common testing methods

Several standardized techniques allow for the evaluation of adhesion according to the nature of the coating and the substrate:

• Pull-off test : a pad is glued to the coating, then pulled off perpendicularly using a dynamometer. The force required for removal is measured (in MPa) according to ISO 4624 or ASTM D4541 .
• Cross-cut test : The coating is cut in a grid pattern according to ISO 2409 or ASTM D3359 , then subjected to an adhesive strip pull test. The classification (from 0 to 5) reflects the degree of film detachment.
• Blister rate assessment : carried out according to ISO 4628-2 , this method allows quantification of the appearance of blisters on the coating after exposure to accelerated conditions (humidity, heat, salt spray).
• Peel or shear test : used for thin films, adhesives and composites according to ISO 8510 or ASTM D1876 .

The tests can be carried out at room temperature or under simulated conditions (humidity, immersion, thermal cycles) to reproduce the aging of the material.

Industrial applications

Adhesion testing is relevant to a wide range of sectors:

• Packaging : control of cohesion between multilayer films, varnishes or barrier layers;
• Industrial paints and varnishes : evaluation of the durability of decorative or protective coatings;
• Materials and polymers : validation of bonding or overmolding processes;
• Aeronautics, automotive and building : durability and resistance tests of surface protection systems;
• Functional coatings and nanomaterials : verification of the adhesion of metallic, ceramic or polymeric deposits on technical substrates.

Technical characteristics and interpretation of results

The results obtained are expressed in units of force (N/mm²) or as a standardized visual classification (ISO 2409, ISO 4628). They allow for the comparison of different processes, formulations, or surface treatments.
Good adhesion is characterized by a cohesive break (within the coating or substrate) rather than an adhesive break (coating/substrate interface).

YesWeLab guarantees tests carried out under controlled conditions, by partner laboratories accredited to ISO 17025 and compliant with COFRAC , ensuring the reliability and traceability of the results.

YesWeLab Expertise and Support

Thanks to a network of laboratories specializing in mechanical and physicochemical testing , YesWeLab supports manufacturers in characterizing surface performance and qualifying materials .
Our technical team helps you choose the most suitable method based on your coatings, substrates, and regulatory requirements.
Test management is simplified through our digital platform , which allows you to track your requests, send samples, and receive your test reports online.

Further analyses recommended

To complement the evaluation of the mechanical and surface properties of your materials, YesWeLab also offers:

• Abrasion and friction resistance tests
• Coating hardness tests
• Flexural and tensile tests on polymers

These additional services enable a complete characterization of surface performance , essential to guarantee the quality, durability and conformity of materials used in demanding sectors such as packaging, aeronautics or automotive.

Contact YesWeLab today to schedule your adhesion tests or get a personalized quote. Our experts will guide you toward the method best suited to your technical and regulatory constraints.