If your teak is white or nearly white after cleaning, the chances are very good that the top 5 to 30 thousandths of wood are dead or devoid of teak resin.  The result of this condition is a substantial weakening of the first few thousandths of the surface of the wood. This weakening of the surface will result in premature separation or pealing of whatever you use to finish your teak.

The solution is to sand off the white wood to expose the live wood that is hidden below. Regarding sanding; There is already a post on this blog that addresses sanding teak and you really need to read it.

Example of lightly checked teak wood.

The real problem comes when the white wood exists on decking. Decking needs to be rough or checked to reduce or eliminate hydroplaning when you are walking the deck when it is wet.  So, what can you do?  Wet sanding the top of the checking will reduce the required effort considerably. Using course bronze wool to scrub away the white wood down in the checking will remove the dead wood without removing the ridges.  Yes, it’s a lot of work, but if you are restoring a classic teak boat, it’s worth the effort and will result in great looking teak that will hold a finish much longer. A note on course bronze wool, it is really sharp so wear leather gloves when you use it

Using caustic cleaners (containing sodium hydroxide) is one of the primary root causes of white teak. These cleaners including chlorine and oxygen bleaches are fast and easy to use, but they do not remove the dead white wood. In fact these harsh cleaners are largely responsible for the condition and they also etch away the micro fibers that hold the main fibers of the wood together. Further, even applying oxalic acid to neutralize the sodium hydroxide is not completely effective and leaves enough active sodium hydroxide to continue etching the your teak for a long time to come.

If you are cleaning boat decking, there is another wrinkle.  Between each plank of decking there is  rubber like cocking that is supposed to seal water out from between and under the  planks.  Many of the cleaning products and pressure washing causes the rather tenuous bond between the teak and the cocking to break down and leak.  Using less aggressive cleaning chemicals is one of the answers to preserving the bonds.

Using oxalic acid or various degreasers to remove the yellow and gray teak resin is much less destructive than the other types of cleaners and they produce a better result. Additionally, cleaning the surface of your teak will make what ever finish you decide to use as a finish stay put longer. Hopefully, the finish you choose has a UV blocker so that the Sun does not destroy the finish and turn the wood gray under the finish.

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A small role and sheet of 80 belt sanding material

Sanding teak or any oily hard wood is not likely to become “fun” but it can be considered to be a labor of love when the proper conditions exist. What are those conditions? Well, having a friend or partner is pretty high on the list, a good supply of cold drinks helps too, but having the right materials and equipment make the most difference.

In 2003 I decided that a teak refinishing business was a smart thing to do to make money, so I rented a 1200 sqft shop and put up a website and contacted all the lawn care people to get names of people who had nasty looking teak furniture. Though the business failed to meet expectations I learned plenty about finishing teak wood.

I got a contract with a local assisted living facility that had lots of teak yard furniture. After sanding a couple hundred teak benches that were really raunchy I found that the sand paper I usee was everything to reducing the pain to a minimum.

I used all sorts of sand “paper” and found all of them, including the so called waterproof ones to be totally useless. They loaded up and came apart in just a few minutes wet or dry!

Soooo, one Saturday when I was browsing through the local flee market and found some industrial grade belt sanding material ends (small rolls too short to use in the intended machine) in grits from 36 to 200. I bought the smallest rolls of each grit and went home smiling.

Very close up view or 80 grit industrial belt sanding material.

The next day I went down to the shop with my treasures and started testing each grit on the teak bench that was next in line to be finished. To my surprise, if the word “BONDED” showed up on the back the material, it was waterproof. If it didn’t it generally wasn’t waterproof. This is important because dry sanding teak with any kind of sanding material is useless. The wood and the sanding material load up in less than 1 minute and generally ruin the paper because you can’t get the wood dust and teak resin  off the sand “paper”.

The next thing I discovered was that anything over 100 grit was just about useless for my purpose. Also, anything under 50 grit was just too course and caAused lots of little “C” scratches no matter how light I pressed on the sander.

Speaking of sander, a jitterbug air sander did the best job of the the sanders I tried. An electric “Palm Sander” worked pretty well too, but it will not stall like the air sander if you put too much pressure on it. And belt sanders are way too aggressive.  A 2 second laps of attention is enough time for a belt sander to do considerable damage.

View of the fabric backing of industrial belt sanding material

If you don’t have an jitterbug air sander and a 120 psi 6 cfm air supply you’re stuck with an electric sander. Even so, the possibility of getting an electric shock while wet sand with a double insulated palm sander is very low, provided you don’t dip the sander in a bucket of water while you’re standing in a puddle of water.

If you simply put enough pressure on the sander to position it, the sander and the belt sanding material will do all the work for you and not damage the wood.

Unfortunately power sanders don’t work for tight places like in between boards. There  you need to be using one of the medium grit sanding sponges made by both 3M and Norton.  For really tight spots there is a wedge shaped sponge that fits perfectly and does really well. The sanding sponges are water proof and need to be wet while sanding to prevent loading.  The motion of these sanding block should be along the grain as much as possible. Cross grain sanding will leave scratches that are difficult to remove.

What I found to be acceptable for preparing any teak (both furniture and marine applications) with moderate to heavy checking was 60 to 80 grit bonded belt sanding material on a 4 by 7 inch Jitterbug air sander.  You use no real pressure on the sander, but you need to keep the wood wet (not flooded) to keep the sanding dust and teak resin (wax) from loading up the wood and sanding material. Even wood that had the remains of varnish or urethane finishes was no problem, though using some MEK based stripper did make the process much faster.

Wet sanding does cause the grain to rise if the wood is left wet for an extended period of time. If the wood is rinsed and dried promptly very little grain rise occurs.

Sanding teak will smooth the finish and restore the beautiful color of the wood, but it does not prepare the wood for finishing. Anytime you remove wood from teak, you expose new teak resin which prevents finishes from bonding or adhering to the wood. Using sodium hydroxide (part A of most 2 part cleaners), sodium hypochlorite (bleach), hydrogen peroxide, and most acids attack the micro fibers that hold the big fibers of the wood together.  Fortunatly, teak does not breath so these products can’t soak in more that a few thousandths of an inch sparing the bulk of the wood from their damage. However, they do weaken the surface where whatever finish you apply attaches to the wood. When the surface wood seperates from the rest of the board, the finish fall off too.

Just a note of sanding teak decks, steps and swim platforms. Checking is a good thing and should not be removed completely because it provides an escape for water and pond slime that is on your wet feet. This escape mechanism is critical to avoiding slips and falls due to hydroplaning on the wood.

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• Never ever use steel wool on or even around your teak. It leaves fragments of steel that will rust and discolor your teak. Once steel wool fragments are embedded in teak, they are very difficult to remove.
• Never ever use a steel bristled brush on your teak. They leave fragments that rust too.
• Never use break fluid, automatic transmission fluid, motor oil, sodium hydroxide, chlorine bleach, or acids stronger than oxalic acid on your teak!
• Belt sanders are really great tools for grinding away lots of wood. Don’t use them on your teak. They are just too hard to control. Palm sanders (electric) and Jitter Bug sanders (air driven) work great. Dry sanding works poorly regardless of the type of sander used. Wet sanding with waterproof sanding material works really well. The sanding material you are looking for is fabric backed belt sanding material that has “RESIN BOND” printed on it. Use 60 to 100 grit material
• Using sand paper finer than 100 grit directly on the wood (even wet sanding) causes wood dust and teak resin to build up in the grain of the wood and on the sand paper. If you want a furniture finish, do the fine sanding on the TeakGuard, not the wood.

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The blessing is: Teak’s very heavy oils greatly retard the tendency of the wood to rot or become vulnerable to bugs and worms. They also give teak the beautiful color and texture we all love. Leaving unprotected teak in the sun brings these natural oils to the surface, where they dry (oxidize) to a what some consider a lovely gray.

The curse is: Because teakwood is saturated with a very heavy oil, it can not breathe like most non-oily woods do. As a result, even tiny amounts of water, trapped between a sealing finish and the wood will vaporize when exposed to the Sun and cause a great deal of pressure to accumulate between the wood and the sealer.

Eventually and generally within a few weeks of hot sunny weather, the UV light makes the sealer brittle and small shiny blisters and/or tiny cracks begin to appear. These cracks allow the water vapor to except during the day, but, at night when the dew forms on the sealer and the temperature falls, water (dew) is drawn into these cracks as the air and remaining water vapor between the sealer and wood begin to cool and contract. As this cycle continues the cracks get larger, the areas of sealer not adhered to the wood grow and begin to peel off. The exposed teak, now open to the air and sun, will allow the teak oil to oxidize and turn gray. Additionally, the unprotected teak is open to mold growth and the associated discoloration.

TeakGuard Finish stands alone in that it allows moisture (water vapor) to escape by “breathing”, while at the same time sealing in the woods natural oils and protecting them from oxidization and discoloration caused by UV light.

TeakGuard’s combination of UV absorbers and reflectors, provide a high degree of protection from ultraviolet rays, to further extend the life of both the TeakGuard finish and the wood.

TeakGuard’s polymer resin do not support mold or mildew growth, but if mold is left on the wood during the cleaning and preparation process, it will continue to grow on the wood under the TeakGuard.

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• Never ever use steel wool on or even around your teak. It leaves fragments of steel that will rust and discolor your teak. Once steel wool fragments are embedded in teak, they are very difficult to remove.
• Never ever use a steel bristled brush on your teak. They leave fragments that rust too.
• Never use break fluid, automatic transmission fluid, motor oil, undiluted ammonia, sodium hydroxide, chlorine bleach, or acids stronger than oxalic acid on your teak!
• Belt sanders are really great tools for grinding away lots of wood. Don’t use them on your teak. They are just too hard to control. Palm sanders (electric) and Jitter Bug sanders (air driven) work great. Dry sanding works poorly regardless of the type of sander used. Wet sanding with waterproof material works really well.
• Using sand paper finer than 100 grit directly on the wood (even wet sanding) causes wood dust and teak resin to build up in the grain of the wood and on the sand paper. If you want a furniture finish, do the fine sanding on the TeakGuard, not the wood.

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5 year old furniture with new TeakGuard finish applied

Congratulations, on your purchase of a set of teak wood furniture. If you care for it properly it will be part of the estate that your children will be fighting over.  Teak furniture even in the far north and deep south will stand up to the worst mother nature can throw at it save the occasional hurricane or tornado.

Weather you leave your furniture completely unfinished, oil it,  seal it or use a breathable finish, consistent care will make you furniture last for at least one life time.  The difference between the various finishing techniques is how much labor is involved in maintaining the finish.

By the way, any time you see teak or teak wood, it includes woods like ipe, iron wood, rose wood, and all the hard oily tropical woods as well as cedar and cypress .

Unfinished Teak

If you choose the unfinished look for your teak, it will turn gray in several months. If that was all that happened life would be very good in deed. However, that is not all that happens. Mold will grow on both the grayed teak resin that migrated out of the wood and on the wood itself.  Often moss will grow where dirt accumulates. The net result is that the surface of your teak will soon require cleaning and the surface of the wood will begin to become very ruddy or checked. This is primarily due to the action of the mold and moss eating away the softer parts of the wood while leaving the harder wood (year rings).

Oiling your Teak

Coating teak with tung oil or lemon oil certainly makes it look good after cleaning the wood with detergent, TSP or oxalic acid. It protects the wood for 1 or 2 months and then needs to be washed off and replaced with fresh oil. Further oil actually promotes the growth of mold and though the mold feeds primarily on the oil itself the wood is often involved.

Insolently, teak wood is so dense and filled with resin that it can only absorb a very small amount of cleaner, finish or oil, the rest just lays on top of the wood.

Using Sealing finishes

Sealing finishes like varnish, urethane, epoxies, and sealing polymers do a really good job of sealing out all the stuff that is likely to damage your teak.  Some are better than others based on the exact mixture of UV reflective or absorber products included in the product.  These finishes will normally last one or two years, though many can not tolerate the hot sun or cold winters  for more than a few months. The root issues that control the life of a sealing finish is:

1. How fast the finish becomes hard and brittle and
2. How much water was trapped between the surface of the wood and the finish

The trapped water vaporizes when the sun shines on it causing a very tiny gas pocket to form on top of the teak and under the sealer. Each time the sun goes behind a cloud the pocket disappears because the water vapor condenses back into water. This cycle of heating and cooling can happen many times a day. Each time each gas pocket gets slightly larger. Eventually, adjacent gas pockets will combine into one pocket and eventually become a blister that will ultimately fail along the edge and fall off. These blisters are not repairable and require that the finish in the entire area be removed and reapplied.

Finishing with a breathable finish

There are a very few breathable (gas permeable) finishes available. All are made from water soluble acrylic polymers. Being water based has its own challenges. The number and color of UV reflective additives is very limited. The number of color additives that will not leach out is also very limited. The polymers ability to bond with other finishes and non wood materials is very limited.

These short comings demand that the wood being coated be free from wax/teak resin and any previous finish except water soluble acrylic polymers. This can be a tall order for boaters with deep (but necessary) checking in their decking,  swim steps and platforms.

Cleaning off old finishes using MEK stripes really work pretty well but they smell really bad and can damage your gel-coat. Using special degreaseers cleaners to remove the teak resin completes the cleaning. Fortunately, this cleaning process only has to be done once because refreshing the finish can be done by simply washing the finish with soap/detergent and water, and applying a fresh coat or two of polymer.

There is one issue with breathable finishes that should not be overlooked or under estimated. Breathable finishes are a double edged sword. They breath both directions. When they become wet from rain, cleaning or use (as in boat) the finish darkens until the water evaporates. This is not a problem until you mix the water wine, or colored food in which case the finish will acquire the color of the wine or food.  This problem can be easily avoided with furniture by occasionally waxing the surface with pure carnuba wax.  This wax must be removed with a mixture of water, detergent and ammonia before re-coating the surface with additional polymer.

Removing stains is possible by removing (sanding away) just the stained polymer finish and  a little of the surrounding area, re-cleaning the wood and re-coating the area with polymer until it matches the surrounding area.

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