EMSL Analytical, Inc.

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ASTM G21 Method


The ASTM G21 test method utilizes various fungal species to determine how synthetic polymeric materials are able to hold up to fungal growth.  Although the actual synthetic polymer component is often resistant to fungi because it does not serve as a carbon source for growth, other components may allow for its growth and the subsequent degradation of the material to be tested.


The method allows for various conditions of fungal growth (moisture, humidity, temperature, salts & minerals).  The synthetic polymeric materials are exposed to the following fungal species during testing procedures:


  • Aspergillus niger


  • Penicillium pinophilum

  • Chaetomium globosum

  • Gliocladium virens

  • Aureobasidium pullulans


The standard test time for incubation is 28 days.  Each sample is observed for any visual effects and rated on a 0 to 4 scale.  The samples can then be analyzed for any effects to their physical, optical or electrical properties.


EMSL’s network of laboratories in the United States and Canada maintain a wide range of accreditations and participate in numerous proficiency programs. These proficiencies, accreditations and certifications ensure that EMSL meets the highest standard of quality and can deliver reliable and consistent results every time.

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