Surface mould growth on five modified wood substrates coated with three different coating systems when exposed outdoors

Modified wood has potential for above ground use, but surface treatment might be a request in such applications. Three coating systems were applied on furfurylated Scots pine, acetylated Scots pine, heat treated Scots pine, oil heat treated Scots pine, heat treated Norway spruce, and eight reference wood substrates and exposed outdoors to evaluate their ability to resist surface mould. Samples of the surface were taken for fungal identification to examine any relationship between treatment and fungal species. Both water-borne and solvent-borne coatings with various fungicides were included and the test was carried out according to EN 927-3. The degree of mould growth mainly varied with time and type of paint. Of the modified wood substrates furfurylated Scots pine had the lowest degree of mould growth and acetylated pine had the highest after 3.5 years. A brown semi-transparent acrylic paint had the lowest degree of mould growth after year 1, year 2.5 and year 3.5. Larch heartwood, copper-organic preserved pine and pine heartwood performed best as wood substrates. No differential patterns in susceptibility to various fungal species were detected on the surface of the coated wood substrates - Aureobasidium pullulans was the dominating species on all the wood substrates.

[1]  H. Militz,et al.  Performance of finishes on wood that is chemically modified by acetylation , 1998 .

[2]  R. Dickie.  Chemical origins of paint performance , 1994 .

[3]  Olaf Schmidt,et al.  Wood and Tree Fungi: Biology, Damage, Protection, and Use , 2006 .

[4]  R. S. Williams,et al.  Adhesion of paint to weathered wood , 1987 .

[5]  A. Pizzi,et al.  Durability of heat-treated wood , 2002, Holz als Roh- und Werkstoff.

[6]  M. H. Schneider.  New cell wall and cell lumen wood polymer composites , 1995, Wood Science and Technology.

[7]  P. L. Brelid,et al.  Acetylated wood – Results from long-term field tests , 2007 .

[8]  P. L. Brelid.  Acetylation of Solid Wood. Wood Properties and Process Development , 1998 .

[9]  P. Ahola.  Moisture transport in wood coated with joinery paints , 1991, Holz als Roh- und Werkstoff.

[10]  G. Kinsey,et al.  Statistical methods applied to field colonisation of coatings by fungi. Part 3: Ecology analysis , 2006 .

[11]  Mats Westin,et al.  Properties of furfurylated wood , 2004 .

[12]  S. Bardage.  Colonization of painted wood by blue stain fungi , 1997 .

[13]  George Daisey,et al.  Mildew and mildew control for wood surfaces , 1999 .

[14]  W. Cooke.  An ecological life history of Aureobasidium pullulans (de Bary) Arnaud , 1959, Mycopathologia et mycologia applicata.

[15]  P. Ahola.  Adhesion between paint and wood substrate , 1991 .

[16]  Arthur Seymour Jennings,et al.  Paints And Varnishes , 2008 .

[17]  S. Jämsä,et al.  Long‐term natural weathering of coated ThermoWood , 2000 .

[18]  P. Larsson Brelid,et al.  Resistance of acetylated wood to biological degradation , 2000, Holz als Roh- und Werkstoff.

[19]  M. Schneider,et al.  Eco‐efficient wood protection: Furfurylated wood as alternative to traditional wood preservation , 2004 .

[20]  J. A. Schmitt.  The microecology of mold growth , 1974 .

[21]  W. Feist,et al.  The effect of surface roughness on the performance of finishes. Part 1. Roughness characterization and stain performance. , 1995 .

[22]  Á. Machuca,et al.  The effect of copper on the growth of wood-rotting fungi and a blue-stain fungus , 2008 .

[23]  R. Horvath,et al.  Paint Deterioration as a Result of the Growth of Aureobasidium pullulans on Wood , 1976, Applied and environmental microbiology.