MIL-STD-810G Method 508.6 Fungal Resistance Test

The MIL-STD-810G are a series of laboratory standards designed by the United States military to test the endurance capabilities of materials based on the expected field conditions they will meet during their lifetimes. Method 508.6 is a material fungal resistance test developed to determine if the material components comprising the test substance will be sufficient to resist fungal growth in an environment simulating ideal environmental growth conditions. As such, the test is performed in a climate-controlled environmental chamber under well-regulated warm, humid conditions.

Test materials that undergo MIL-STD-810G method 508.6 testing are inoculated with a suspension of fungal spores via a light and even aerosol spray. For the duration of the test, they are suspended in the environmental chamber and observed periodically for the presence of fungal growth on the test surfaces.

Summary of the MIL-810G 508.6 Method

• Environmental chamber is set up with proper water content to ensure humidity.
• Fungi are grown on solid medium with a spore suspension prepared form the following fungal genera (requisite species listed in official method):
  • Aspergillus
  • Penicillium
  • Chaetomium
• Positive control test strips are dipped in growth promoting solution and placed evenly throughout chamber with test samples to ensure spore viability.
• The pooled spore suspension is sprayed directly onto control and test samples.
• Control and test samples are evaluated periodically for fungal growth.

Strenghts of the MIL-810G 508.6 Method

• The method provides stringent testing conditions to mimic an extreme environment ideal for fungal growth.
• The test challenges materials with a wide variety of fungal species.
• The test can easily be adapted to include several species of fungus for custom projects.
• The test uses easily accessible, low tech tools and standard microbiology supplies.
• Provides a high degree of confidence in a product’s ability to resist fungal growth.

Weaknesses of the MIL-810G 508.6 Method

• The method compares growth under static temperature and humidity parameters, whereas real product usage may be better represented by a range of temperatures and humidites in some instances.
• The method does not account for real-world conditions due to human activities, such as regular cleaning of the surface.
• The scoring system is subject to interpretation which can lead to variability across labs.
• The test offers little information about the product’s long-term performance.