Table 2.

Criteria for assessing mould resistance.

Fungal Growth Class	Evaluation of Fungal Growth	Product Category	Product Performance
Class 0	No sign of growth under the microscope.	Category 0	The material is not a nutrient medium for microorganisms (it is inert or fungistatic)
Class 1	Growth invisible to the naked eye but clearly visible under a microscope.
Class 2	Increase visible to the naked eye, covering up to 25% of the test area.	Category 1	The material contains nutrients or is so poorly contaminated that it allows very little growth
Class 3	Visible growth to the naked eye, covering up to 50% of the test area.
Class 4	Considerable growth, covering more than 50% of the test area.	Category 2–3	The material is not resistant to fungal attack; it contains nutrients that allow micro-organisms to grow.
Class 5	Strong growth, covering the entire test area