Formaldehyde testing methods

The manufacture of wood-based materials has, until now, mainly been carried out with formaldehyde-containing binders. As a result, formaldehyde from wood-based materials and their products can be released into the indoor air. For years, it has been suspected that formaldehyde can cause cancer; on 1 April 2015, its classification as "probably carcinogenic in humans" became legally binding.  As a partner of the wood-based materials industry, we not only test products regarding formaldehyde but also use our years of experience for the optimization and further development of the testing methods.

Testing of formaldehyde in wood-based materials

Since the mid-1970s, the formaldehyde release into the air from particle board and other materials has been measured under defined, reality-simulated conditions in a test chamber developed at the Fraunhofer WKI. The test chamber became the fundament for legislation on formaldehyde testing in Germany and is today an integral component of a European standard. Simultaneously to this, simple test methods were developed in order to carry out the evaluation of wood-based materials with regard to the release and the content of formaldehyde in wood-based materials within short time periods. These test methods should exhibit a correlation to the test chamber procedure and the limit values derived therefrom should serve the manufacturers in their in-house laboratories regarding the continuous monitoring of the produced wood-based materials.

Testing methods for the determination of formaldehyde in wood-based materials

For the evaluation and classification of wood-based materials with regard to formaldehyde, country-specific legal requirements exist.

Europe

• reference procedure: test chamber method EN 717-1
• derived test methods:
• perforator method EN 120 / EN ISO 12460-5  
• gas analysis method EN 717-2 / EN ISO 12460-3

America

• reference procedure: chamber method ASTM E 1333
• derived test methods:
• small chamber ASTM D 6007
• desiccator method ASTM D 5582
• desiccator method JIS A 1460
• perforator method EN 120 / EN ISO 12460-5 
• gas analysis method EN 717-2 / EN ISO 12460-3
• DMC (Dynamic Micro Chamber)                             

Focuses of our work

• Determination of formaldehyde in the test chamber in accordance with the international standards EN 717-1, ASTM E 1333, ASTM D 6007, JIS A 1901, EN ISO 16000-9, prEN 16516, GOST
• Determination of correlations from the derived test methods to chamber procedures
• Perforator method EN 120 / EN ISO 12460-5 
• Gas analysis method EN 717-2 / EN ISO 12460-3
• Desiccator methods (ASTM, JIS)
• Research projects on the further development of testing procedures
• Currently: Modification of the gas analysis method EN 717-2 / EN ISO 12460-3

Limits of the known testing procedures

At the beginning of the measures for the modification of particle boards for the production of particularly low-formaldehyde boards in order fulfil the requirements in accordance with CARB Phase 2, it became clear that a correlation between the two test methods appeared to be increasingly critical and that through the determination of the formaldehyde content, no conclusions concerning the emission in a test chamber could be drawn.

Within the framework of research projects on this topic at the Fraunhofer WKI, investigations were carried out to determine the correlation of the test chamber method and the perforator method EN 120 as well as the gas analysis method EN 717-2 on modified particle board. Through specialist agreements and scientific publications, we have presented the results to the general public.

These investigations have shown that the sufficient accuracy required in order to perform a calculation of universal perforator or gas analysis limit values does not exist.

On the contrary: a product-specific consideration would be necessary for the determination of the correlation of the reference method (test chamber method) and the methods used in the in-house factory production control (perforator or gas analysis method) for these modified low-emission particle boards.

Further development: Modification and optimization of testing procedures

Within the scope of a research project, we are currently revising the procedure for the determination of the formaldehyde release in accordance with gas analysis method ISO 12460-3 with the participation of the International Association for Technical Issues related to Wood (iVTH) as well as the wood-based materials industry, standardization bodies and manufacturers of testing equipment.

The aim of the project is the optimization of the procedure with regard to analysis and testing duration as well as the integration of these findings into the standardization process.