AbstractA quat-silicone micro-emulsion (particle size <40 nm), an amino-silicone macro-emulsion (110 nm), and an alkyl modified silicone macro-emulsion (740 nm) were used to modify Scots pine (Pinus sylvestris L.) sapwood. Treated and uncoated boards were exposed to natural weathering for one year along with water treated controls according to EN 927-3. The treatment with silicone emulsions did not enhance the color stability, which was assessed at three months intervals using a spectrophotometer and classified according to the CIE-Lab system. Treatment with amino-silicone emulsions gave a more yellowish appearance of the wood surface before weathering than the other silicones and the control. Boards treated with quat- and amino-silicone were less overgrown by staining fungi and displayed reduced surface roughness than those treated with alkyl-modified silicone and the control samples.