160 Oil-Based Undercoater is a premium exterior primer that offers excellent hiding, sealing, and mildew resistance. This high solids, full-bodied product is designed for wood surfaces and has been specially formulated with a linseed oil-alkyd resin that allows the primer to be flexible and extremely durable. #160 has also been designed to have excellent adhesion,which is extremely important in repainting new and weathered surfaces. The linseed oil used in this product’s resin system allows for superior penetration with the potential to make older dry wood look like new. This product is recommended for use on all types of wood, including weathered and dried pressure treated wood and ferrous metal surfaces. #160 is the product of choice for priming bleeding woods such as cedar or redwood to stop the tannin bleed through. This product is not recommended for aluminum, galvanized metals or masonry surfaces. Some knotholes may require shellac to stop the tannin bleed through.