The timber is heat treated by the Yakisugi process and therefore has improved longevity. However, most people want the colour to remain consistent over time. Without an oil stain the wood will change colour over time just like any other natural product. Some people embrace the natural patina aesthetic, and look forward to the organic, colorful weathering. With Yakisugi, owners have the choice of doing maintenance or not. Re-oiling can be done as a periodic maintenance, or the patina can be enjoyed as it develops over the decades. Also most owners want the soot to be bonded into the surface with an oil stain so that it doesn’t come off when touched. Another reason we use oil stain prefinishes is that most designers or owners want a specific colour or look, and since all exterior grade oil stains have a pigment load as the primary UV inhibitor, the designer or owner can decide what colour they want their siding to be.