Teak is the most desirable wood in the world to use for exterior trim on boats and yachts, and is in constant demand despite its outrageously high prices of up to $20 per board foot. The reason that teak works so well on boats is that it has an extremely high natural oil content that makes it resistant to decay. A piece of raw, untreated teak can last for decades just lying on the ground exposed to sun, rain and ground moisture. Because of this high oil content, teak can be a difficult wood to work with, as it is hard to glue or coat with many types of modern finishes.
For many applications on a boat or yacht, the best finish for teak is no finish at all. This is especially true of teak decks or steps. Teak also contains silica which makes it a great non-skid surface when wet. Teak decks are unequaled as a surface to walk on when the decks are wet with waves or rain. Putting any type of finish on such a deck simply ruins it and destroys this desirable characteristic. Teak decks do, however, weather with age and turn silvery gray. This is also desirable up to a point, but all deck decks require sanding ever so often to bring back the natural light brown color and prevent deep grooves from being caused by this weathering. This sanding will over the course of many years result in the need to replace the deck, but if it was thick enough to begin with, such replacements should only be necessary once or twice in the life of the yacht.
Teak is used in many other places on boats besides decks or steps, though, and while some people also leave these wood parts bare, most prefer some type of finish to highlight the natural beauty of the wood. Rub rails, covering boards, door and window trim and hatches are all areas where finished teak is desirable. The simplest means of finishing these teak parts is by rubbing them down periodically with oil to supplement the natural oils in the wood and prevent drying out. Many boat owners swear by oiled teak and would use no other finish. But oiling teak still does not produce a highly finished look. Most owners would prefer their teak to have a high gloss finish that is often referred to in marine woodworking as “brightwork.”
Brightwork is the art of finishing wood with varnish or clear polyurethane. The preferred finish for brightwork is spar varnish that is formulated to block ultraviolet rays from the sun. The enemy of brightwork is not water, but rather the sun, which can cook off a fine finish and reduce it to a peeling mess in just a matter of months. This is why it pays to buy the best spar varnish available. Cheaper finishes are not worth the effort required to put them on. Spar varnish on your exterior teak requires a commitment. You can’t simply varnish your wood and then forget about it. Instead, you must go back at least twice a year and lightly sand the finish and apply two more coats. These coats are “sacrificial” and will break down in the sun but protect the underlying coats which should have been put on 5 to 7 deep when you first finished your wood.
Some boat owners have sought out lazier methods of achieving brightwork, such as by applying clear polyurethane instead of varnish. It lasts longer than varnish, but when it does break down as it eventually will, it is much more difficult to remove for refinishing. Another varnish substitute commonly seen on teak is called Cetol. Cetol is much easier to apply and lasts longer than varnish, but it turns your teak an ugly orange-brown color that is both unnatural and mostly opaque, hiding the natural beauty of the wood grain.
The traditional way to achieve a brightwork finish on teak is with spar varnish. Stick to good spar varnish and stay on a maintenance schedule and your teak will gleam. Leave your decks and steps unfinished, but keep them sanded when needed, and they will never let you down as an unparalleled non-skid surface.
