Ultraviolet (UV) light has a negative influence on durability of wood. In order to increase durability of wood, it should be protected. Lignin, that is the component of wood with the most important influence on its colour, is highly susceptible to photo degradation. Wood can be protected against UV-light also Norway spruce wood and on thermally modified Norway spruce wood was performed. The presence of TiO2 particles on wood was confirmed with the SEM analysis. The specimens were subsequently coated with a commercial oil-based product for protection of wood in exterior. The samples were exposed to UV-light and colour and gloss were measured. During 14-day long exposure it was found, that in terms of colour changes the most stable was thermally modified Norway spruce wood with the deposits of TiO2, and wood with a surface film of the cured oil. The worst colour stability was exhibited by non-modified Norway spruce wood. The results showed that particles of titanium dioxide on thermally modified spruce wood increase its resistance against UV-light, while the TiO2 particles in a combination with the oil did not provide protection against UV-light. Contact angles of water were higher on the specimens with oiled surfaces. Up take of water into wood is decreased by protection with titanium dioxide and oil.
|
