S-1 is a two-part clear, penetrating, waterproof, epoxy sealer. It is completely waterproof and suitable for use above and below the waterline. If you are doing any kind of outdoor project or build – boat or Adirondack chair, sealing the wood prior to assembly or even after means the wood will move less and water will be less likely to get underneath the finish, which will prevent mold and mildew from growing and destroying your finish and wood. Trust us, Spar Varnish and any outdoor rated finish is not enough, so do what savvy boatbuilders do and put this down first. Your finish and furniture will last a lot longer. Mix ratio is a simple 1:1 and coverage is approximately 75 square feet per quart.