Spar varnish is what you use on wood that lives outside. Boats, outdoor furniture, exterior doors. It’s formulated to handle sun and water where regular varnish fails.
What Makes It Different
More oil, more flexibility. Regular varnish dries hard and brittle. Spar varnish stays somewhat pliable because wood expands and contracts outdoors.
UV blockers. Sunlight destroys unprotected finish. Spar varnish contains additives that absorb UV before it damages the film.
Where To Use It
Exterior wood exposed to weather. Boat trim and rails. Outdoor furniture. Front doors that get direct sunlight.
Not ideal for indoor furniture or flooring. The softer film shows scratches more easily than polyurethane.
Application
Thin the first coat 25% with mineral spirits. It penetrates better and builds a good base. Subsequent coats can be full strength.
Sand lightly between coats with 220 grit. Dust thoroughly before the next coat.
Plan on 3-5 coats minimum for real protection. More coats = more durability.
The Maintenance Reality
Spar varnish isn’t permanent. Expect to recoat annually on things like boat rails that take serious abuse. Maybe every 2-3 years on shaded furniture.
Before the old finish fails completely, scuff sand and add fresh coats. Much easier than stripping everything and starting over.
Brands I’ve Used
Epifanes is excellent but expensive. West Marine sells good stuff. Minwax Helmsman works fine for furniture.
The premium marine brands really are better. Worth it for anything important.
Quick Tips
Apply in shade, not direct sun. Hot surfaces make varnish set up too fast.
Thin coats beat thick ones. Thick coats sag and take forever to cure.
Don’t varnish in high humidity. Moisture causes clouding.
