This is a fantastic, tung oil based, marine-grade varnish, suitable for both outdoor and indoor use. Provides excellent protection from weathering and the elements, including UV rays and salt water. Ideal for boats, outdoor furniture, exterior doors, sills and more. Superior to polyurethane because it is flexible enough to expand with the wood, resists cracking and peeling, and adheres well to oily woods like teak and mahogany. Flows on freely for easy brushing. Not suitable for continuous submersion.