An expert woodworker reveals some homely truths about teak
Issue 40 : Jan/Feb 2005
Separating myth from reality almost impossible with a wood as well known as teak. From its “discovery” by the Dutch in the 1600s to today’s confusing maintenance and political debates, few imported wood species have been as publicized and consequently misunderstood as Tectona grandis. For boat restorers, teak can be anything from a significant maintenance bugaboo to an attractive accent used in interior and exterior applications. But it’s far from the perfect wood for all nautical applications. Moreover, it’s important to know its working quirks and short-comings before messing around with lumber that routinely costs between $15 to $25 a board foot retail.
Dutch treat or trick?
Teak is desirable in boatbuilding today for many of the same reasons it has been prized for centuries. The wood is hard, heavy, rot-resistant, and, when grown naturally in its native habitat, quite attractive. Those are the main reasons why today’s boating enthusiasts love it — those and the lore of teak.
In its native growth areas of Southeast Asia, teak has always been considered a sacred wood. For thousands of years, teak was used to build temples and shrines and frequently was the basis of religious sculpture. The myths got their start when the first Dutch explorers realized the financial value of including this kind of background information in the sales pitch for the lumber back home. Certainly, teak’s prime selling points 400 years ago were its practical values. But since then the legends about teak grew and changed without ever really diminishing.
For those doing boat projects using wood, however, teak has some inherent problems worth considering. Even if you’re willing to pay the high cost of the wood, the extra labor involved in working teak is more time-consuming than it would be working other attractive woods like the mahoganies or an appropriate domestic species. For instance, when sawing or shaping teak, blades will dull much more quickly because of the wood’s high silica content. Moreover, teak is a relatively brittle wood. So in crosscutting operations, there is often chipping near the edge of the cut, particularly when cutting with blades that have been dulled by the silica. Taking extra time out to score the cutting line with a razor knife prevents chipping and drags out a simple chore.
In working with teak for the last 25 years or so, I’ve found another unpleasant side effect is its toxicity. Skin rashes and asthma-like breathing problems are often reported among woodworkers who work with teak frequently. Also, the primary sensitizing agent in teak can set off more sensitivity to allergens in other unrelated wood species. So it’s best for anyone working with teak to take the time to use a respirator at the very least and perhaps also suit up in a pair of disposable coveralls.
Teak will also slow down restoration operations because it will clog sandpaper more rapidly than most other hardwoods. This is due to the wood’s oil content, which helps give teak its legendary durability. The wood’s silica also contributes to sandpaper clogging. Clogged sandpaper drags out a job and makes it more expensive than working with some other woods because more sandpaper is needed.
There are other woods that meet or exceed teak in durability — without the attendant oil, allergy, and blade-dulling problems. Among domestic hardwoods, mesquite, white oak, black walnut, and several species of cedar compare nicely with teak for decorative value. Some cedars, juniper, and Douglas fir can match its durability in exterior applications. Among imported woods, most mahoganies, Spanish cedar, purple-heart, Angelique, and sapele are just a few substitutes that spring to mind as good all-around replacements for teak — at a significantly reduced price too.
Extra care in gluing, finishing
Teak’s natural oils, which are responsible for its superior rot-resistance, also play havoc with ordinary gluing and finishing procedures. Teak oils tend to concentrate at the wood’s surface, particularly as the wood dries. This is good for repelling water, making teak a good wood for decks. But those oils are not good for many adhesives and finishes.
When gluing teak, there are two approaches that help assure a long-lasting bond. The best is to plane the mating surfaces just before gluing. A common practice is to wipe the mating surfaces with a lacquer thinner, acetone, or alcohol before gluing, but this is not a good idea. Capillary action from evaporating solvents pulls more oil to the surface. Nor should you simply run a belt sander over the surfaces to be glued. The heat generated in sanding may bring out more oil. It’s also wise to use a less oil-sensitive adhesive like resorcinol or epoxy.
In the finishing department, a different approach to teak is also required. For best results in a hard finish, a good sealer coat is essential. The most reliable sealer to use is epoxy resin. But be sure to use an epoxy resin specially formulated for coating, not gluing. After applying epoxy, be certain to wash the dried surface with clear fresh water. Otherwise, you’ll have trouble with the drying time of your oil-based varnish overcoat. Amine blush is a chemical byproduct of the epoxy curing process. If left on the sealer surface, the drying time of topcoats of ordinary oil-based varnish could be extended by many hours, sometimes days.
In exterior and interior applications, some boatowners prefer an oiled finish for teak. This sidesteps the sealer issue but adds an annual maintenance chore that can become burdensome. In exterior service, most non-pigmented teak oils simply do not survive a season in the sun, salt, and abrasive traffic. For 25 years, I’ve tried one teak oil formulation after another and — even in Maine’s relatively benign summer climate — the non-pigmented exterior oil finishes haven’t held up.
By the end of the boating season, the golden-brown look of my freshly oiled teak surface was always closer to dull gray. Pure 100-percent tung oil holds up best and often will survive an entire season in northern latitudes. Pigmented teak oils also work well, but they color the wood orange or brown.
In exterior and interior applications, oiled teak tends to collect and retain dirt, which inevitably builds up in the wood’s open pores. Some older boats, therefore, not only end up with their teak surfaces faded gray but also in desperate need of a cleaning before they can be oiled.
Teak cleaner torment
Most of the teak cleaners on the market use a chlorine bleach base or an oxalic acid base to get the gray out of lightly aged teak. Most of these potions are watered down to minimize the risks involved in the cavalier use of these chemicals by consumers. Thus, they often require several applications to bring back the teak’s original color.
Ultimately most teak cleaners are only effective at removing the gray patina and light dirt. Long-term mildew stains, motor oil drippings, diesel fuel discoloration, and a host of other common messes usually require sanding to get the wood truly clean . . . a time-consuming job. Thus, on anything other than exterior decks, I would recommend varnish over teak oil. In the long run, it is far less time-consuming.
Political correctness problems
Teak may have always had its maintenance bugaboos, but these days there is another angle to consider. Teak increasingly comes with built-in social/political considerations. If you’re thinking of ordering some teak, you may want to consider them too.
Since the 1600s, there has generally been a wholesale stampede to process teak into lumber, continuing essentially unabated until the 1980s when Thailand finally banned teak exports in an effort to conserve the resource. That ban has been only partially effective, and other countries’ conservation efforts have been even less effective. Also, whether teak-processing today is continuing at a sustainable pace is a matter of some debate. Many industry officials say it’s under control, but groups concerned with environmental degradation and associated human-rights violations disagree vehemently. Most teak-related problems focus on the outlaw nation of Myanmar, formerly known as Burma. Myanmar has an abysmal human rights record and isn’t much interested in environmental concerns either. Unfortunately, it’s not easy to avoid purchasing native teak from Myanmar, which is the world’s biggest teak exporter.
The diminishing supply of forest-grown teak has led to a rise in teak plantations in Central and South America, as well as the West Indies, Africa, and some Southeast Asian countries. Teak trees actually regenerate relatively rapidly and are tolerant of a wide variety of tropical soil and weather conditions. So plantations have been appearing in increasingly large numbers since the 1950s, with a rapid escalation in the last 20 years or so. But no government, educational, or industry agency that I contacted could produce statistics that show how much imported teak comes from plantation stocks or how much is from naturally occurring forests.
Important debate
The debate over plantation vs. native teak is important to boat restorers because of anecdotal evidence that plantation teak may not possess some of the desirable qualities that natural teak possesses. The problem could be the New World soils where much of the plantation teak grows. The difference in Eastern and Western soils may also explain why Central and South American plantation teak is generally much lighter in color than its Southeast Asian counterpart. The chemical content of the soil in which any tree grows has a direct bearing on the rot-resistance and durability of the lumber from that tree. Variable soils will produce fluctuations in any wood’s rot-resistance.
Ultimately, you must rely on your teak retailer for information about your teak’s origins and exactly what you can expect from it. Some retailers are cooperative in this regard, while others are not. A thorough knowledge of what teak ought to look and feel like, as well as how it ought to work, should keep you out of trouble.
Forest-grown teak from South-east Asia is characterized by its color: a rich, deep brown to a dark golden-brown, both of which turn darker when exposed to sunlight. The sapwood is a few shades lighter and should be avoided where rot-resistance is of prime concern. When cut or planed, the surface of natural teak develops a decidedly oily feel to it. Note, too, that Southeast Asian teak has the distinct smell of old shoe leather when sanded, cut, or planed.
By contrast, New World plantation teak is a much lighter yellowish color, akin to straw or old hay. When worked, the classic teak smell isn’t as evident and, in some cases, is absent altogether. The surface’s oily feel is usually present, but it’s frequently not as pronounced as that of forest-grown teak. And, U. S. government studies of Central American plantation teak indicate the wood is not as strong or tough as forest-grown teak. Still, in both plantation and forest-grown versions, teak’s strength and toughness are generally on a par with those of many North American oaks.
As a straight-grained wood, teak has an exceptional stability — especially the heartwood. But whether it’s fine-grained or coarse-grained may depend on whether it’s plantation- or forest-grown, old growth or new. As with most wood species that regenerate rapidly, the tree’s growth rings tend to be widely spaced in ideal growing conditions found on plantations or on freshly logged open areas. Widely spaced growth rings usually yield a coarser grain. But a teak tree that has struggled for decades to reach above the canopy of the natural rain forest will have tightly packed growth rings and a resultant fine grain.
Some alternatives
Teak today still maintains its tradition of being one of the most popular woods among all imported species. It has that “Cadillac image.” Still, slight variations in its popularity have had an unpredictable effect on price. For instance, when tax policies put the boatbuilding industry in a severe recession during the early 1990s, teak prices lowered to $6 to $10 per board foot. But once tax policies changed and the industry rebounded, retail teak prices bounced up to as much as $14 a board foot in early 1996. With the recent boatbuilding boom, some shops have been paying as much as $20 per board foot and even more for the very best. Other factors, including the plantation-grown vs. forest-grown debate, can also affect the price. When labeled, plantation teak is usually less expensive than forest-grown.
Teak veneer is a much cheaper alternative, bringing the price down to as little as $4 to $6 per square foot. And less expensive teak plywood is available in many thicknesses and styles, including flat-sawn, quarter-sawn, and book-matched. But some enterprising woodworkers have worked successfully with teak substitutes.
Afrormosia (Pericopsis elata) is perhaps the most common teak substitute. By looks and heft alone, it’s hard to tell the difference between the two. Tough and durable, it’s not quite as oily as teak, but it is equally rot-resistant. Rhodesian teak (Baikiaea plurijuga) is similar to afrormosia, although it is more difficult to find in long lengths. Iroko (Chlorophora excelsa and C. regia) is also considered a dead ringer for teak. All three woods are forest-grown in Africa and can be 10 to 30 percent cheaper than teak.
Even cheaper is Spanish cedar (Cedrella spp.), which can be one-half to one-third the price of teak. It has excellent rot-resistance but is not quite as hard or tough as teak. I’ve used it in many exterior applications, including handrails and toerails. To compensate for its lower strength, I increase the scantlings.
Teak may be nice, but it’s not critical on a boat. Given the price and the availability of alternatives, it may be worth considering a substitute the next time you’re confronted with the question: to teak or not to teak?
Thank you to Sailrite Enterprises, Inc., for providing free access to back issues of Good Old Boat through intellectual property rights. Sailrite.com
