We take the natural charm of Doug Fir Shiplap siding and factory machine finish each board with a high-quality oil-based primer. The primer is available in off white, gray or it can be custom tinted to your choice of color. Factory applying the stain to all six sides (also known as back priming) provides protection against water and harmful UV rays from the sun. Note: We recommend top coating the siding within 30 days to ensure maximum performance and adhesion. Remember to seal all boards that are cut on-site during installation to eliminate any chances for moisture to get into the wood siding. All primed boards should be kept clean and dry on-site prior to installation.