Uncoated siding in coastal areas naturally turns a soft driftwood color after years of exposure to the sun and salt air. To accelerate this process without leaving siding susceptible to rot, Cabot developed a product called Bleaching Oil back in the late 1800s. Basically it's a lightly pigmented, semitransparent oil-based stain that contains a special bleaching agent. Once it's brushed onto new, uncoated softwood siding, such as cedar, fir, or cypress, the surface changes to a light gray in about 6 months to a year. Recoat every 3 to 5 years.