In search for more natural, non-toxic construction materials, interest towards surface charred wood has increased. Charred boards can be used in several applications, especially as exterior claddings or fences. The weatherability of surface charred boards depends on several factors, of which the charring method has a high impact. A gas flame will create a severely degraded structure that is rather inert in use, but the has poor resistance to mechanical abrasion. Contact charring at a lower temperature creates a hard, smooth surface, but the wood components may still be chemically and biologically reactive. To evaluate the outside performance of surface charred spruce, a natural weathering test was implemented. The goal was to assess the changes in surface properties and appearance, as well as compare two different techniques: a hot plate/contact charring combining a moderate temperature with a long modification time, and flame charring that produces a heavily charred surface within a short time.
Keywords: surface charring, weathering, wood
Authors
Maija Kymäläinen
Aalto University, Department of Bioproducts and Biotechnology; PO Box 16300, FI-00076 Aalto, Finland
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