Fungal Test - GR testing per ASTM G21
Standard Practice for Determining Resistance of Synthetic Polymeric Materials to Fungi
GR Testing per ASTM G-21 evaluates resistance to fungal growth. Test pieces are placed on a nutrient salt agar surface, inoculated with a mixture of 5 different fungi and then incubated for a minimum of 28 days. After incubation, fungal growth is evaluated using a 0-4 rating scale with 0 being no growth, and 4 being heavy growth.