The Problem of Reducing the Leachability of Boron by Water Repellents

Boron as a wood preservative with several ecological advantages is of great interest and an enlargement of its use to replace agents more toxic to humans may be of advantage. However, its leachability prevents a broader application. Possibilities of hydrophobising boron treated wood and thus to reduce leaching were investigated by laboratory tests. The results demonstrate that boron diffuses even at moisture contents below 20%. Thus leaching can not be affected by hydrophobic agents placed on the inner surface of wood because diffusion still takes place in the cell-wall. Surface coatings have some protective effect. Nevertheless the best way to prevent leaching is the logistical protection by storing and using boron-treated wood under roof. Only for a short-time leaching risk, for example during construction, a surface protection with waxes or resins may be useful