What Is Fogging?
The fogging test measures the tendency of volatile substances released, under heat, from vehicle interior materials to condense on a cold glass surface and form fog and film. Since this deposit causes visibility impairment on the windscreen, it is a direct safety issue.
Purpose of Fogging
The purpose is to quantify the material's tendency to leave condensable substances on glass, and to demonstrate compliance with OEM specifications.
Which Products Is Fogging Applied To?
- Instrument-panel and interior-trim plastics
- Seat foam, leather and synthetic leather
- Carpet and headliner
- Adhesive and sealing materials
- Cable insulation materials
In Which Sectors Is Fogging Used?
Standards Related to Fogging
- DIN 75201
- ISO 6452
- SAE J1756
Fogging Conditions
- Method A
- Reflectometric (gloss) method — gloss loss on the glass is measured
- Method B
- Gravimetric method — the substance deposited on aluminium foil is weighed
- Specimen temperature
- Held at the heating temperature prescribed by the standard (commonly 100 °C)
- Cooling plate
- The condensation surface is kept at a fixed low temperature (commonly 21 °C)
Equipment for Fogging
- Fogging tester (heating bath and cooling system)
- Gloss meter (for the reflectometric method)
- Analytical balance (for the gravimetric method)
- Glass plates and aluminium foils
- Conditioning chamber
Sample Requirements for Fogging
- Specimens cut to the diameter prescribed by the standard
- Generally at least three specimens
- Layer structure must be preserved in composite material
- The specimen surface must be clean and untouched by hand
Duration of Fogging
Heating time varies by method (commonly 3 or 16 hours); together with conditioning and measurement, the total duration is a few days.
Fogging Procedure
- 1Specimens are cut and conditioned.
- 2The glass plate or aluminium foil is prepared; its initial gloss or weight is measured.
- 3The specimen is placed in the glass vessel, and the top is closed with the condensation surface.
- 4While the specimen side is heated, the condensation surface is kept cold.
- 5At the end of the specified duration, the condensation surface is removed and conditioned.
- 6Gloss is measured in the reflectometric method, and weight gain in the gravimetric method.
- 7The result is reported as a fogging value.
Fogging Acceptance Criteria
The acceptance criterion is defined in the OEM specification. A limit is set on the percentage of remaining gloss for the reflectometric method, and on the deposited-substance quantity (mg) for the gravimetric method; limit values vary by material group.
Evaluation of Results
A high fogging value indicates an excess of plasticiser, processing aids or residual monomers in the material. Interpreted together with VOC/FOG results, source identification becomes easier.
Fogging Report
- Applied standard and method (A or B)
- Specimen identification
- Heating temperature, duration and cooling temperature
- Fogging value for each specimen
- Comparison with the specification (if available)
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 authorisationsRelated Regulations
- OEM interior-material specifications
Otomotiv Testleri — What Does This Testing Field Cover?
The section below describes the field that the Fogging 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 Fogging
Should the reflectometric or the gravimetric method be used?
The customer's specification determines this. The reflectometric method measures the visual effect (gloss loss), while the gravimetric method measures the quantity of deposited substance. Some specifications require both.
Are fogging and VOC testing the same thing?
No. VOC testing identifies the released compounds and quantifies them; the fogging test measures the visual effect that this release creates by condensing on glass. The two are related but measure different quantities.