Measuring adhesion strength with DeFelsko PosiTest AT adhesion tester

Adhesion testers for paints, varnishes and coatings

Products mentioned:

PosiTest AT-A, PosiTest AT-M

Adhesion testers for paints, varnishes and other coatings

Adhesion is the ability of a coating such as paints and varnishes to adhere to a substrate, which is called "substrate adhesion," or the ability of a coating to adhere to multiple layers in the system, which is called "intercoat adhesion." For coatings to work properly, they must adhere to the substrate to which they are applied, such as metal, concrete, wood, and other materials.

What is an adhesion test?

In accordance with ASTM D4541/D7234, ISO 4624 and others, adhesion testers evaluate the adhesion (peel strength) of a coating by determining the greatest tensile force it can withstand before peeling. Failures, evidenced by broken surfaces, occur along the weakest plane within the system consisting of the dolly (loading device, peel nozzle), adhesive, coating(s) and substrate.



The PosiTest AT series of adhesion testers measures the force required to peel a specific test diameter of coating from its substrate using hydraulic pressure.

Why is it necessary to test the adhesion strength?

The objective of adhesion testing is to produce a coating failure. Coating adhesion is an indicator of how well the surface has been prepared and how well the coating has bonded to the surface and/or additional coating layers. Adhesion testing provides a quantifiable method to determine whether a paint or coating system is fit for purpose and can meet the quality requirements of the job specifications.

Choose between manual or automatic PosiTest AT adhesion testers:

Automatic adhesion tester

PosiTest AT-A

Electronically controlled hydraulic pump automatically provides consistent and continuous trigger pressure. Significantly reduces user effort and the risk of interfering with the pulling process.Impact and scratch resistant color touch screen with keypad for operation with or without glovesUser adjustable pull speed, pull limit and hold timeBuilt-in battery performs over 200 tests per battery chargeInternal memory stores maximum trigger pressure, pull speed, test duration, dolly size, pass/fail, type of break and user notes for 100,000 pull bond tests in up to 1,000 blocks.

Manual adhesion tester

PosiTest AT-M

Manual hydraulic pump that generates a uniform and continuous pressure with a single strokeHigh-contrast, easy-to-read color displayPull force indicator for manual monitoring and adjustment of the pull forceThe internal memory stores the maximum trigger pressure, trigger speed, test duration and dolly size for up to 200 pulls

Determination of the type of coating failure (addition to step 5):

Detailed analysis of the fracture - is it a cohesive fracture, an adhesive fracture or failure of the adhesive?

Please watch these videos on adhesion testing with the PosiTest AT adhesion tester:

PosiTest AT Automatic adhesion tester from mtv messtechnik

The automatic adhesion tester PosiTest AT offers absolutely uniform tensile force! - No more rejects due to one-sided peeling!

Works without any effort and always delivers exact results. PosiTest AT Automatic Adhesion Tester is used for #tear-off testing