Spar Varnish Satin Quart
System Three Spar Varnish is a urethane enhanced film finish formulated to protect against the harshest salt water and marine environments, as well as provide protection for your outdoor projects....
The number one enemy of an outdoor film finish is moisture that gets into the wood and underneath the finish. Moisture makes its way into the wood via the wood actually breathing (a result of not sealing the wood off from ambient moisture in the air), as well as through micro fissures in the topcoat caused by temperature extremes and UV radiation. So, if you’re contemplating a film finish for your outdoor furniture – consider using a good sealer underneath. A sealer will combat this “breathing” the wood does and be a barrier to prevent moisture from expanding underneath the topcoat, even if it manages to get through the micro fissures. The bonus for this hard work is your finish will look good well beyond what you might otherwise expect…but not forever.
Start with a good sealer such as System Three Clear Coat. If it’s going to be outside all the time all year long and even if it’s not, System Three recommends encapsulating the wood with System Three Clear Coat prior to assembly. This will effectively stop the wood from breathing and provide an excellent base for the topcoat to adhere to plus it will stop moisture from spreading underneath the finish through micro fissures. Please see the PDF from System Three (link on this page) for more information on finishing outdoor wood.
Be advised that even if you follow all these recommendations, you will still need to take steps to care for your project in the off-season and to eventually apply a new coat or two of finish or remove the old finish down to the Clear Coat and recoat the piece. However, following our suggestions will keep your Adirondack chair or other outdoor project looking good longer, and it will be easier to recoat when necessary.