To many people well-finished teak helps define their idea of the perfect Bristol-fashion boat. Others see the work involved in maintaining teak an unnecessary curse. A walk down the paint aisle of your local boat store usually doesn’t shed any light on the problem of maintaining teak, as there are literally hundreds of variations of teak coatings. Varnishes, oils, synthetic finishes, two-part and other modern concoctions all vie for the attention of the teak-challenged boater.
Often, the choice of coating is made based on the amount of time required to maintain a finish on the teak, even though it may not have the desired “look”. However, this article will deal with the problems and techniques of varnishing teak. We’ll leave the other finishes for another time.
The upkeep required for a varnish finish is due to several causes. Wood expands and contracts as it absorbs or releases moisture. This constant flexing eventually causes the varnish to crack. UV rays from the sun also attack the varnish, causing loss of gloss as well as contributing to cracking. Once water finds a crack or break in the varnish, it will begin to stain the underlying wood and further break down the varnish. While the best varnishes are formulated to resist these attacks, eventually they break down and require re-coating.
This is more of a problem the farther south (in the northern hemisphere) you are located. The UV is so intense that the varnish on the exterior wood required recoating every three months or so. It sometimes gets so bad that some boat owners paint their wood trim, so much for the great varnish look.
Getting the deep “look” expected from a quality varnish job requires building up a number of coats of varnish. Some suggest eight coats, others twelve. My wife, who does all the varnishing on our boat, puts on a coat a day and sands between most coats until she gets 6 coats on inside teak and 8 coats on the outside teak.
Prep Work
Like any finish, a proper varnishing job requires proper preparation. If the teak has been previously varnished, it will require sanding (with 220 grit sandpaper) to even out the finish color and remove all loose or cracked varnish. Finishes incompatible with the new varnish will have to be removed (check a small area with the new varnish) by sanding or scraping.
If the teak has never been varnished and is very dirty, use a two-part teak cleaner to get the dirt out and bleach the teak. Stubborn stains, from fasteners for example, can be removed using Oxalic acid wood bleach (FOLLOW THE DIRECTIONS!). Pressure washers or the use of stiff bristle brushes can damage teak. The teak grain is alternately soft and hard. The high-pressure washing or stiff brushes can remove the soft grain leaving the hard grain as ridges in the teak surface.
The resulting finish should be clean, free of moisture oils and dirt and of an even color. As teak is a naturally oily wood, a final wash with acetone will remove the surface oils and prepare the teak for the first coat of varnish. After the acetone wash, use a tack rag to get any remaining dust off the teak.
If the teak is being vanished in place, mask off the surrounding area with high-quality, long-life masking tape. The tape will have to remain in place for many days (if you are applying multiple coats). The cheap tan tape will bond to the surface after a while and will be hard to remove.
Varnishing
There are several varieties of varnish on the market. We have had great results from Interlux Rubbed Effect Satin Varnish for the interior and Interlux Original Varnish for the exterior. Don’t start by shaking the can of varnish; it introduces air bubbles that will carry over into your finish. Use a stirring stick to gently mix the varnish. Decant enough for each coat into a separate container; don’t risk contaminating the whole can or letting the solvent in the varnish evaporate.
Many professional finishers use expensive brushes and guard them with their lives, lavishing considerable care on them. Frankly, I’ve had great success with good quality foam brushes. It’s your choice, but I’d go with the foam brushes.
The first coat of varnish should be thinned about 15% to 20% with the recommended thinner. This allows the varnish to soak into the grain of the teak for better adhesion and sealing. This first, thinned, coat will raise the grain of the teak, so lightly sand with 220-grit sandpaper to remove the “fuzz”.
Subsequent coats can be applied un-thinned. Sand between each coat and clean the surface carefully with a tack rag before applying the next coat. As mentioned above, my wife lays down a coat a day until six to eight coats have been applied. She sands before each coat but the last coat and uses a tack rag to remove any dust.
Once a solid varnish base has been applied, keep a watch on it. Recoat any area that appears scuffed or damaged, preferably before any water has found the area. Once a year or so, depending on your location, lightly sand the varnish and apply a maintenance coat or two.
The Epoxy Alternative
An alternate method of developing a more durable finish while retaining the “look” is to use epoxy as a base. The prep work is the same as with straight varnish. When ready, the teak is coated with epoxy, usually three coats, to fully protect the teak. The epoxy forms a strong and long-lasting base for a final varnish finish.
Avoid coating the teak early in the day. The teak, as it warms up, will out-gas and form bubbles in the epoxy. Excessive mixing of the epoxy will also form bubbles that end up in the finish. The second and third coats can be applied while the prior coat is still tacky. Keep a close eye out for drips and runs, these will be much harder to sand out than varnish runs.
The epoxy must cure completely, usually for more than 24 hours. Wet sand the epoxy being careful not to sand through the epoxy. Be careful in your choice of varnishes, as some varnishes will not dry tack-free when applied over epoxy. If you are using WEST SYSTEM epoxy, the 105 resin and 207 hardener are the best choices. The WEST Epoxy web site has a good section on applying finishes over epoxy at:
http://www.westsystem.com/
Look under the “Using WEST SYSTEM Epoxy” header.
Why apply varnish over the epoxy? Because epoxy has very little protection from UV rays. Applying two or three coats of a high-UV protection varnish will provide the needed UV protection.
Finally
Remember, TANSTAAFL, “There Ain’t No Such Thing As A Free Lunch”. Getting that deep finish on your teak using varnish will take some effort. Once established, it will have to be maintained. You will be the one to determine if it’s worth the effort or not.
Capt'n Pauley
From 18 years as a professional captain and an additional dozen years repairing boats I have these observations...
Varnishing is great if you're getting PAID to do it. Otherwise it sucks.
Stay away from clear epoxy at all costs. When it comes time to redo it, and that time WILL come, it's the devil's own work to strip it down to bare wood.
When I bought my own sailboat I estimated that it would take me fully a work week and a half to maintain the varnish work. I had better things to do with that week and a half a year...like lying in a hammock with an icy cold drink in my hands.
What I did was to lay on three good coats of varnish on all the wood as a base coat and then I put down two good coats of single part polyurethane paint. After three years it was still bright and shiny and I'd saved a month's worth of labor.
The reason for laying down the base coat of varnish was to protect the wood so the paint wouldn't sink into it. Then, at a later date when I came to sell the boat if the new owner wanted to varnish things it would be a simple job of stripping the paint to get to good wood.
Posted by: Richard | June 05, 2009 at 01:58 PM