Wood material has advantages, it comes from a renewable source and it is easy to manage. But one disadvantage when used outdoors is biological discoloration of the material. Some impact on the discoloration is the presence of moisture and nutrients, necessary components for the microorganisms to grow and start a col- onisation. Samples made of Norway spruce (Picea abies (L.) Karst) heartwood or sapwood coated with two different film forming paints was studied. The paints had a binder formula made of alkyd or acrylate. Additional parameters related to study the influence of moisture content on discoloration were high and low density material, with and without impregnation oil. Outdoor exposure was made during five years in the southern part of Sweden. The samples were hung with 45 degree inclination, facing south direction. Visual differences in biological surface discoloration were observed for samples within the same paint, which could be explained by differences in heartwood and sapwood.
Keywords: discoloration, heartwood, sapwood, paint
Authors
Sjökvist T.
Department of Forestry and Wood Technology, Linnaeus University, Växjö
Blom Å.
Department of Forestry and Wood Technology, Linnaeus University, Växjö
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