Totalboat Marine Spar Varnish – Best Outdoor Wood Varnish. Rust-Oleum Marine Spar Varnish – Old Reliable. MCCLOSKEY Voc Mow Spar – Volatile But Effective. Epifanes Clear Varnish – A Great Bargain. System Three Clear Marine Spar Urethane Varnish Coating – The Budget Option. Click to see full answer. Then, what is the best exterior varnish? Epoxy with Exterior Varnish An epoxy sealer with exterior varnish topcoats is the most durable, but also the most labor-intensive finish you can apply to outdoor furniture. This is the finish favored by boat builders so you know it’s going to last a long time.Furthermore, how do you varnish exterior wood? Using the proper application technique provides the most protection for your door with either one. Sand the door in the direction of the grain. Remove the sanding residue with a tack cloth. Thin the varnish with mineral spirits. Apply the varnish with a brush. Allow the varnish to dry for at least 24 hours. Accordingly, what is the best varnish for outdoor wood? Marine spar varnish is the best type for outdoor use. Its key ingredients are linseed oil (pressed from flax seeds) and alkyd resin (made by reacting linseed oil with alcohol and acid). The film is flexible enough to move with wood as it shrinks and swells with shifts in humidity.What is the most durable clear coat for wood?The most common types are lacquer, shellac, polyurethane, varnish and wax. Generally applied with a brush. Varnishes are very durable but are slow to dry, making them susceptible to dust and dirt. Shellac is a fast-drying natural resin that may need to be thinned before applying.