Varnishing Your Wooden Boat
By Don Casey.
Dorothy Parker once famously remarked: “I hate writing; I love having written.” I feel the same way about varnishing. Nothing flatters a boat more than the glow of well-varnished wood, but to bask in that glow, someone must suffer through the process of preparing the wood and applying the varnish.
Almost all woods other than teak will weather and eventually rot if not protected from the elements. Paint is the most effective protective coating, but if you paint wood, all you see is paint. Varnish protects wood without hiding its inherent beauty; ten coats of glossy varnish can transform a merely interesting piece of wood into something achingly beautiful. Dorothy Parker’s sentiment applies: everyone loves varnished wood. It is the varnishing we hate.
Unfortunately, varnish is your only choice if you want to protect exposed mahogany without painting it. As for teak, it can stand the exposure, but due to pollutants in the air, it will more likely turn black than silvery grey if not treated. You can bleach and scrub it back to its original golden hue, but each scouring removes a layer of wood. Exposed screws and popped bungs in teak woodwork are nearly always due to excessive cleaning, not weathering.
What Is Varnish?
Varnish is essentially paint without pigment. It is broadly defined as a transparent hard coating, “hard” being the key word. It is the solid left behind when a liquid mixture of oil and resin dries. In traditional spar varnish, the oil is tung and the resin is phenolic. Today there are many other formulations on the market, but no other transparent single-part coating is more durable in the marine environment than spar varnish.
Most sailors don’t care what’s in the can as long as it goes on easily and lasts a long time. Still, in deciding whether to embrace or shun varnish it helps to know that the can contains some kind of oil, some sort of resin, a quick-evaporating solvent, maybe a drier to accelerate the process, and an additive or additives that boost ultraviolet protection.
READ more at https://www.sailmagazine.com/diy/all-about-varnishing-your-boat