Adhesion Test — ISO 2409 / ISO 4624 / ASTM D3359

What Is Adhesion?

Adhesion test is the test in which the adhesion of the coating to the substrate is evaluated by cross cutting (ISO 2409 / ASTM D3359) or pull-off (ISO 4624) methods. The first method gives classification, the second gives quantitative strength.

Purpose of Adhesion

The purpose is to verify that the coating can carry service loads without separating from the substrate.

Which Products Is Adhesion Applied To?

Industrial paints and primers
Toz kaplamalar
Automotive paint systems
Galvanized and metallic coatings

In Which Sectors Is Adhesion Used?

AutomotiveElectric VehicleBatteryPlasticsRubber

Standards Related to Adhesion

ISO 2409 (cross cutting)
ASTM D3359
ISO 4624 (tear off)
ASTM D4541

Adhesion Conditions

Cross-cut: Blade spacing defined in the standard according to the coating thickness; the result is given as a class 0–5
pulling away: The pasted pin is withdrawn at standard speed; breaking strength is measured in MPa
Kopma tipi: Adhesion or cohesion failure is reported separately
Conditioning: The coating must be fully cured; Conditioned in the environment defined in the standard

Equipment for Adhesion

Cross cutting tool and standard tape
Pull-out device (adhesion tester) and pins
Coating-thickness gauge
Conditioning room

Sample Requirements for Adhesion

The coating must be fully cured; early testing gives low value
Coating thickness determines blade spacing and must be measured
The adhesive must be stronger than the coating when pulled off.
Measurement points should be selected representatively

Duration of Adhesion

Typically 2–4 days including conditioning.

Adhesion Procedure

1Coating thickness is measured.
2Blade spacing or pin is selected according to the method.
3The cross cut is applied and the tape is pulled; or the pin is glued and pulled.
4The result is classified or the strength is calculated.
5The type of rupture is determined and photographed.

Adhesion Acceptance Criteria

The acceptance criterion is given in the specification: maximum class in transverse shear (e.g. not exceeding class 1) or minimum strength in pull-out.

Evaluation of Results

Cross cutting and pulling do not measure the same magnitude and their results are not interchangeable. Testing performed before the coating is fully cured does not represent actual adhesion. When the adhesive breaks during pulling, it invalidates the result.

Adhesion Report

Standard and method applied
Coating system and thickness
Conditioning conditions
Grade or breaking strength
Break type and images

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Paint and coating specifications
ISO 12944 (korozyon koruma sistemleri)

Otomotiv Testleri — What Does This Testing Field Cover?

The section below describes the field that the Adhesion test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Automotive testing shows that a component keeps working under conditions representing the loads it will meet over the life of the vehicle. A vehicle is not a single product but an ENVIRONMENT: vibration, temperature cycling, salt water, stone impact, electrical transients and electromagnetic noise are all present at the same time and for years.

What distinguishes this family is that VEHICLE MANUFACTURER SPECIFICATIONS sit on top of the standards. ISO and SAE publications establish the common ground; but Volkswagen, BMW, Ford, Stellantis, Toyota and Renault define different severity levels, additional tests and different acceptance criteria in their own specifications. For a component, the phrase "complies with automotive standards" is not sufficient on its own; which manufacturer's specification, and which revision of it, must be answered.

The family carries three separate processes together and they are often confused. Homologation covers the type approvals a vehicle needs to enter traffic and runs under state authority. Supplier approval means passing the vehicle manufacturer's own quality and testing requirements and is a commercial relationship. The third is design verification: the engineering team demonstrating that its own design meets its targets.

At component level the test plan is built around the LOCATION OF USE. A module in the engine bay and a module in the boot do not go through the same temperature and vibration profile; a component inside a door and one in the roof console do not see the same water and dust exposure. The ISO 16750 series is the common framework for this location-based approach.

The shift to electric vehicles has reshaped the field. High-voltage safety, insulation coordination, battery safety, charging interface conformity and the electromagnetic behaviour of high-voltage components have been added to the classical automotive test set. In a quiet vehicle, acoustic and vibration expectations have changed too; sounds once masked by the combustion engine are now audible.

The quality system side cannot be separated from testing in this field. A manufacturer under IATF 16949 presents test results in the PPAP file; measurement system analysis, process capability study and the control plan stand around the test report. A single good result is not enough — the process must be shown to be able to repeat it.

Method groups in this field

Environmental and climatic
Temperature cycling, thermal shock, damp heat, salt spray, dust and water ingress (IP), solar radiation. Severity levels vary with the mounting location.
Mechanical
Sine and random vibration, shock, mechanical loads, fastener torque and durability cycles.
Electrical
Supply voltage variations, transients (ISO 7637), reverse polarity, overvoltage, short circuit and sleep current measurements.
EMC
Component emissions (CISPR 25), radiated and conducted immunity (ISO 11452 series), electrostatic discharge (ISO 10605).
Materials and emissions
Odour, fogging and VOC emissions from interior materials; flammability; UV ageing; coating durability and stone impact.
Functional safety and cyber security
Functional safety evidence under ISO 26262 and cyber security engineering under ISO/SAE 21434; these are tied to regulation through UNECE R155 and R156.

Commonly confused in this field

An automotive report without a specification reference is not accepted in the supply chain; which OEM specification and revision was applied must be stated.
Type approval and supplier approval are different processes. A component with E-Mark approval is not thereby considered to have passed the OEM's own acceptance tests.
A result obtained on a prototype does not carry over to series production; PPAP is done with series production parts.
On the EMC side, measuring emissions alone is incomplete; immunity is a separate body of work and is more critical in a vehicle.
On electric vehicle components, high-voltage safety is a distinct competence; classical 12 V test infrastructure is not sufficient.

Which decisions these results support

Supplier component approval and the PPAP file
UNECE type approval and E-Mark marking
Design verification and durability evidence
Root cause analysis of field complaints and warranty returns
Assessing the impact of a design or supplier change

Related Tests

Frequently Asked Questions About Adhesion

Is there a conversion between cross shear class and MPa value?

No. Cross cutting classifies the tendency of the coating to flake off from the cutting edges; Pull-out measures the breaking stress in the perpendicular direction. It is decisive which method the specification requires.