UV Boost - concentrated water-based liquid stain additive that contains a new technology ultraviolet light inhibitor. Some regions of the country such as the southeast, southwest and higher altitude areas are subject to high intensity sunlight. Over time the ultraviolet light in sunlight darkens the lignin component of wood. When added to the first coat of any of our LIFELINE water-based stains, UV Boost combines with the lignin to delay the wood beneath the stain from graying. Since the concentration of the active components differ, be sure to use the appropriate size for the amount of stain or finish you are using. UV Boost is only effective when used in the first coat of stain or finish applied to bare wood. UV Boost must be in direct contact with the wood for it to work. It is not effective when added to topcoats or stains applied over an existing finish. UV Boost may be used in both interior and exterior applications. When used inside it will help prevent the "picture frame" effect.