Fungal infestation in fire protection coatings

Advanced Materials − The Basis of Innovative Buildings

Fungal infestation in fire protection coatings in outdoor areas

© Fraunhofer WKI
Fungal infestation for fungus mixture of Aureobasidium pullulans and Sydowia polyspora.

Discolouration of a façade surface as a result of a microbiological infestation can indicate a severe defect. In the case of wooden façades, microbiological attacks on the substrate itself can lead to its destruction and are therefore far more serious than optical defects. Wooden façade elements therefore require a protective coating, in order to ensure the functionality of the component. However, coating systems on exterior wooden components are exposed to increased infestation through mould and blue-stain fungi. Selective use of biocides enables the avoidance of damage.

The results of the biocide tests show that very low biocide concentrations are sufficient for impeding the fungal growth of the test strains Cladosporium cucumerinum, Altenaria alternata, Aureobasidium pullulans and Sydowia polyspora. Irrespective of the concentration of the biocide used, no fungal growth was determined for the samples which contained biocides. Solely the biocide-free malt extract showed uninhibited fungal growth. With the help of these results, it was possible to determine that a low concentration of biocides (0.05% and 0.1%) should be used for the base coat.