How to Restore Teak Wood on Boats
Probably nothing can make or break the appearance of a fiberglass boat more quickly than the appearance of the exterior teak trim. Contrary to popular belief, teak is not a maintenance-free wood that can be safely ignored and neglected for years at a time. Though teak may not rot, it can check, warp, and look depressingly drab if not properly cared for.
Although it is not immune to neglect, teak is incredibly resilient, and can be brought back to life after remarkable amounts of abuse. Therefore, there is no excuse for drab, ugly exterior teak on any boat.
Unlike other woods used for exterior trim, the grey weathering of teak rarely extends very far below the surface of the wood. Instead of the tedious scraping and sanding essential to restore the weathered surface of, for example, mahogany, a fairly simple chemical cleaning usually suffices to bring even the worst of grungy teak back to a semblance of its original glory.
However, chemical cleaning can be pretty tough on the wood. Most chemical cleaners rely on a caustic and/or an acid to clean and bleach the surface of the wood. Inevitably, these powerful cleaners gradually erode the surface, softening the pithy portions of the grain and leaving raised ridges along the tougher growth rings of the wood.
Chemical cleaners can, however, almost miraculously clean weathered teak. The four-color brochures published by teak care product companies do not exaggerate when they show bright tan teak next to grey ugly teak, claiming that only a few minutes’ work will transform the dirty to the clean.
For best results, however, you should never let your teak trim get to the point that such drastic measures are called for: and once you get it back to “like new” condition, you should be prepared to put in the time and effort required to keep it in that condition.
Cleaning Teak on Boats
If your teak is dark brown from old, oxidized dressing, or weathered grey from neglect, the first step is a thorough cleaning.
The severity of the discoloration of the wood will determine the severity of restorative measures required. Because cleaners containing acids and caustic are hard on the wood, you should try to use as mild a cleaner as will do the job, even though it may take some experimentation and a few false starts to come up with the right combination of ingredients.
The mildest teak cleaner is a general purpose household powdered cleaner such as Spic ‘n Span. A concentrated solution of powdered cleaner and vigorous scrubbing using a very soft bristle brush or, better yet, a 3M pad, will do a surprisingly good job on teak that is basically just dirty. Don't scrub any harder than you have to, and always scrub across the grain. Every time you scrub the teak, you are removing softer wood, which eventually results in an uneven surface that raises the grain. Regularly using a firm brush to scrub with the grain will lead to problems down the road.
The advantage of a gentle scrub using mild cleaners is that while it is more work for you, it is by far the most gentle for your teak. Since you are likely to have some powdered detergent around, always try this method before going on to more drastic measures.
Simply wet down an area with water, clean with the detergent solution, rinse with fresh water, and let it dry. If the wood comes out a nice, even light tan, you’re in luck. If it’s still mottled or grey, a more powerful cleaner is called for.
The next step is a one part cleaner specifically designed for teak, or the equivalent. These can be either powdered or liquid. Most consist of an abrasive and a mild acid, such as phosphoric acid or oxalic acid. They are more effective in lightening a surface than a simple detergent scrub. Many household cleaners like Barkeeper's Friend contain oxalic acid.
If the cleaner contains acid, however, some care in handling must be taken. It is advisable to wear rubber gloves and eye protection using any cleaner containing even a mild acid.
The cleaning procedure with most one-part cleaners is the same: wet the teak down, sprinkle or brush on the cleaner, scrub down, and rinse off. Be sure to rinse well.
Even badly weathered teak should come up reasonably well with a one part cleaner. When the wood dries, it should be a uniform light tan. If some areas are still grey, a repeat cleaning should do the job. If, however, the teak is still mottled or discolored, the time has come to bring out the heavy guns, and with them the heavy precautions.
The two part liquid cleaners are, with only a few exceptions, powerful caustics and acids which do an incredible job of cleaning and brightening teak, but require care in handling to avoid damage to surrounding surfaces, not to mention your own skin.
While the instructions on all two-part cleaners are explicit, a reiteration of the warnings on the labels is useful.
Adjacent surfaces, whether gelcoat, paint, or varnish, must not be contaminated by the cleaners, most of which can bleach gelcoat or paint, or soften varnish. Constant flushing of adjoining surfaces with water while cleaning is usually adequate, but masking off of freshly painted or varnished surfaces may be more effective.
Hand protection, in the form of rubber gloves, is absolutely essential. In addition, do not use these cleaners while barefooted, and preferably not while wearing shorts. Eye protection is also a good idea. The chemical burns which can result from some cleaners can be disfiguring and painful. If the product label has the key words “caustic”, “corrosive”, or “acid”, wear protection and avoid splashing!
There is slight variation in the instructions for the various two-part cleaners, but the general principles are the same:
1. Wet the teak down;
2. Apply part one (the caustic), spreading and lightly scrubbing with a bristle brush;
3. When the surface is a uniform wet, muddy brown, apply the second part (the acid), spreading with a clean bristle brush;
4. Apply and spread enough of the acid to turn the teak a uniform tan;
5. Rinse thoroughly, and allow to dry completely.
It is fairly common to use almost twice as much of the second liquid (the acid) as the first, in order to get uniform light color. For this reason, it’s a good idea to buy an additional bottle of the second solution, when it is available. Despite the fact that most manufacturers package two-part cleaners in kits of two equal-sized bottles, they usually make additional bottles of the second part available.
Unless the instructions require it, do not rinse off the muddy brown surface of the teak after it has been treated with the caustic. You will be washing unneutralized, corrosive liquid all over the rest of your boat. Thorough neutralizing with the acid wash will minimize problems.
Surface Preparation for Finishing
A freshly cleaned teak surface is a joy to behold, but it won’t stay fresh, clean, and light for long if you don’t take care of it. In fact, the surface will begin to oxidise instantly as it dries. The sooner you complete treatment after cleaning, the better.
Teak, like many woods, has grain which varies a great deal in hardness, even within the same piece of wood. Over time, even a simple scrubbing with detergent will wear away the softer portions of grain, leaving ridges of harder grain. The irregularity of such a surface merely accelerates the rate at which it gets dirty again.
Before getting out the sander to smooth out the grain, however, look at both the function and construction of the wood you’re dealing with.
If the teak surface you’ve cleaned is teak-faced plywood, there’s a good chance that a thorough sanding to smooth the surface will go right through the layer of veneer, effectively ruining the piece. On the typical fiberglass sailboat, veneered or plywood components include conpanionway drop boards, hatch tops, and sometimes cockpit seats and soles. Before sanding any of the parts, examine them carefully to see if they are solid lumber or veneer. Since exposed edges of plywood are sometimes covered with veneer strips to make them look like solid lumber, you must look pretty closely.
Although decks are usually solid lumber, they also can present problems. If the decking is much less than 1/2" thick, and has plugged (bunged) fastenings, sanding out the grain ridges may sand away enough material to sand through or loosen the bungs, exposing the fastenings.
Even when bungs are set in epoxy, they require a counterbore at least l/8" deep to hold them in place.
Even if the grain is quite pronounced on laid teak decks, you may be better off living with a cleaned irregular surface than opening Pandora’s box by trying to create a perfectly smooth surface.
On other solid teak items such as handrails, toerails, and Dorade boxes, thorough sanding of the chemically cleaned surface before treating with a sealer will result in a much more attractive surface.
Do not, as we have seen many times, attempt to restore badly weathered and grey teak by sanding before chemical cleaning. Chances are that you will quickly discover that a discouraging amount of sanding is involved, and you will end up using a chemical cleaner in any case. Sanding both before and after treatment is a waste of effort, and is likely to remove more wood than is necessary. On teak with pronounced surface irregularities, it could take forever to sand them out to get a uniform surface color, while chemical cleaning will quickly lighten even the deepest gouges or grain defects.
Wait until the cleaned teak is thoroughly dry before sanding or applying teak dressing.
Sanding of cleaned teak is not always required, particularly if the surface is to be treated with an oil-type dressing rather than a gloss finish such as varnish. Surface irregularities show far less with the matte finish of teak oils.
Granted, perfectly smooth teak is likely to be more even in color, and some esthetic sensibilities are offended by a surface showing pronounced grain pattern. From a simply functional point of view, however, irregularities are unimportant except in terms of simplified cleaning in the future.
Unless you intend to put in the effort required to maintain your teak between major cleanings, sanding the teak smooth is a waste of time. The next chemical cleaning will simply repeat the grain-raising cycle, requiring another sanding.
If you swear you’re going to keep the teak up, however, a good sanding will enhance the wood’s appearance.
The safest tool for general sanding is a high speed orbital sander such as the Makita B04510. If you use successively finer grades of aluminum oxide sandpaper, and don’t slow the machine down by applying pressure, it will leave a smooth, relatively swirl-free surface suitable for finishing with a teak dressing.
Inexpensive, heavy, slow-speed orbital sanders should be avoided. They leave telltale swirl marks on the surface which are accentuated by the application of finish, and their sanding is generally too slow.
Never use a disc sander on a surface to be finished bright (oiled or varnished), unless you are one of the few experts who really know how to handle this potentially destructive tool.
The same goes for the belt sander. It is perhaps the most efficient tool for smoothing large, flat surfaces, but is capable of doing heartrending and irreversible damage in the hands of the inexperienced. For decks and hatches of solid lumber, the belt sander is the answer - but only if you are thoroughly experienced with the tool, and only with a heavy duty machine that has a large sanding surface.
When power sanding, always mask off adjacent areas of gelcoat. Even lightly touching a polished gelcoat surface with a sander will damage it. The same rule applies for hand sanding.
Remove masking tape immediately when sanding is completed. Even leaving the tape on overnight on an exterior surface is likely to make it difficult to remove. Tape adhesive residue can be removed with a mild solvent, such as alcohol, and gentle rubbing with a coarse cloth, such as a piece of toweling.
After sanding, remove sanding dust from all surfaces with a vacuum cleaner. If electricity is not available, sweep thoroughly with a dusting brush or a large paintbrush which will no longer be suitable for painting because it is full of sanding dust. Obviously, you don’t sacrifice your best badger hair brush for this. The cheapest bristle brush will do fine.
Applying a Finish to the Teak
The final step in rejuvenating an exterior teak surface is the application of a dressing or sealer to retain for as long as possible the appearance of the freshly prepared wood.
Our own preference is a dressing which does not darken the wood. For our top-recommended sealer check out the six-month results of our ongoing test of wood finishes. For really durable finishes on teak trim, or caprails, there are a variety of options. Search under wood finish, or teak treatments to turn up our most recent wood finish test results. This article on varnishing also has some good tips.
The choice of a teak dressing is, however, as much a matter of esthetics as function. Look around at the boats whose exterior teak looks best to you, and query the owners about the products they use.
A major caveat is in order. No exterior teak finish lasts very long. For optimum results, monthly application of dressing is required, with a good scrubbing with detergent and water before applying a fresh coat. You’re kidding yourself if you think a once-a-year treatment will keep your teak looking good.
Do not attempt to use household-type furniture oils for exterior teak. They will not stand up to the weather.
Whatever teak dressing you use, be neat in applying it. Slopped-about teak dressing may not show when it first gets on fiberglass, but it inevitably darkens with age, leaving stains that look just as bad as varnish spills, and are just about as hard to remove. Clean up spills and overruns immediately with a rag dipped in mineral spirits unless another solvent is specified by the manufacturer of the dressing.
Masking tape is not particularly effective in protecting surfaces from spills of teak dressings, as the viscosity of most dressings is so low that they simply bleed under the edge of the tape. The answer is careful application, and careful cleanup.
Maintaining Your Teak
Your job isn’t over when the last coat of dressing is applied. To look its best, exterior teak needs frequent attention. With a boat used in salt water, frequent washdowns with fresh water will prolong the life of the dressing, but scrubbings with salt water and a brush will reduce it.
Horizontal surfaces, such as hatch covers, will require more frequent coats of sealer than vertical surfaces, such as companionway dropboards. High traffic areas like a teak cockpit sole will require the most attention of all, but are the easiest to scrub and retreat, since sanding is not usually desirable.
If all this sounds like a lot of work, that’s because it is. That explains why the exterior teak on so many boats looks so grubby.
It is still, however, less work than maintaining a varnished exterior teak surface - a lot less. If you really think you want varnished teak, try maintaining a clean oiled surface for a season first.
Few things look better on a boat, particularly a white on white fiberglass boat, than well-maintained exterior teak trim. An owner who neglects exterior wood is likely to be the same owner who rarely changes the oil in the engine, and who rarely bothers to put on the sail covers after a day’s sail when he expects he’s going sailing again tomorrow.
Owning a boat isn’t all play. A boat is a major investment, and like most investments, the more attention you pay to it, the more it will return. The time you put into maintaining your exterior teak is well invested. The return is not only pride of ownership, but dollars in your pocket when the time comes to sell the boat.