I’ll never really understand the allure of teak decks. It’s true they give good footing if they aren’t varnished and wet, but there are other solutions for keeping a grip. No, they won’t look as good, but they won’t compromise the watertight integrity of a perfectly good deck due to the thousand-or-so holes in it. I’ve always felt that the prime directive with boats is to do everything you can to keep water on the outside.
Teak is a wonderfully tough wood. It looks great either treated or if left to weather in its natural state so it develops a silvery gray patina. The trouble is that contamination and dirt — airborne, waterborne, and the gifts of birds and people — turn that beautiful patina into a black or dark gray mess. In the old days decks were cleaned by wetting them and rubbing with blocks of soft sandstone. However, there isn’t enough teak in decking now for that to be a useful approach.
So let’s clean your deck — and any other exposed teak.
1. First and foremost, never use a wire brush — brass or otherwise — to clean teak. In fact, avoid stiff brushes altogether. Use sponges, sponges with a mild abrasive material on one side, or rags of diaper material or terry cloth. Bronze wool is a very good choice.
2. Two-part teak cleaners use acids that can eat away the soft pulp of the teak, leaving hard ridges of lignin standing proud. It looks terrible and is uncomfortable on unprotected parts of your anatomy. You’ll have to sand it, and that means removing teak, which is almost as expensive as gold. If you’re not careful some cleaners can damage unwaxed gelcoat by etching it. One-part teak cleaners, which require more elbow grease, also may contain acid.
3. The best teak cleaner I’ve found is trisodium phosphate, or TSP. It’s inexpensive, relatively safe and readily available in most hardware stores, supermarkets and boating supply stores. (Guess which source is most expensive.) TSP comes in crystals, and two or three tablespoons in a gallon of water is a good starting point.
4. Wear kneepads and protective gloves. Apply the solution with a sponge and leave it on for no more than five minutes to let the surface grunge lift. If you leave TSP on too long it will lift the grain and eat the pulp portion of the wood, just like teak cleaners that contain acid. Rinse and scrub with a bronze wool pad. If the wood is so deeply soiled it won’t come totally clean, repeat the treatment.
5. As a last resort, you may have to bleach the wood to lighten it. Teak brighteners contain bleach, likely oxalic acid. Bleaches will damage the surface of the teak, so be careful using them. If money is a factor, mix your own solution of oxalic acid in a bucket of water, but go easy with it and rinse thoroughly.
6. If you have lignin ridges despite your precautions, the only solution is to sand the teak. Use a random orbital sander with 120-grit paper. Vacuum or brush the resulting dust, and wipe the surface with a tack cloth.
7. If you’ve got teak trim, put a teaspoon or so of TSP in a spray bottle of water and go to work with a bronze wool pad, cleaning only those areas that are soiled.
8. Now that the deck is clean, how do you keep it looking good? Varnish looks beautiful, but it’s a chore to apply and maintain. Also, the surface can be quite slippery when wet, though you can apply grit to the varnish to make it non-skid. UV radiation and abrasion from foot traffic will make this a short-lived and labor-intensive solution.
9. Teak oil works well and nourishes the wood. It must be reapplied several times a season, especially in the Sun Belt.
10. Sealers work well and can last a long time. Maintenance and repair are less labor intensive.