We performed surface charring of spruce wood with the flame treatment, and compared its surface effects on selected properties with the influence of thermal modification of wood in vacuum. The samples were analysed with the method of FTIR spectroscopy, we measured contact angles of distilled water, formamide and diiodomethane and calculated the surface free energy. The treated samples were coated with a transparent coating and its adhesion strength was determined with the pull-off test method. The results indicate that the effects of flame treatment are similar to those caused by thermal modification in vacuume, in the case of selected surface properties. When the samples are heat treated in vacuume, bulk modification occurs, while in the case of flame treatment only the surface is affected. Charring of wood with a flame burner is in comparison with thermal modification in vacuum faster, cheaper, economically more efficient and less demanding.
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