Teak wood often has very large, prominent pores, which can make it difficult to achieve a smooth finish. If you prefer a more rustic finish, there's no need to fill the teak and cover the pores and natural grain. If you'd prefer a smoother, glasslike finish to your wood, fill the pores and grain using a wood filler prior to sealing or finishing. Wood filler is different from wood putty and consists of sand, gypsum, wood flour and a binding agent. It won't shrink after it dries, so the surface of the wood remains smooth and stable.
Wood filler comes in both water- and oil-based varieties. Water-based versions dry faster and are easier to apply. They can be applied using a nylon abrasive pad to fill all holes and pores, and a stiff card or scraper should be used to immediately remove excess filler. Once the filler dries, sand the surface of the teak smooth using a 220- to 320-grit sandpaper. If you prefer more working time, use an oil-based wood filler. Thin this product with mineral spirits according to the instructions on the package, then brush on using a paintbrush. As the filler starts to dry and develops a hazy look, use a piece of burlap to rub the filler into the pores and grain. Rub the material diagonally against the grain until all pores are filled and excess filler has been removed. Once the filler dries, sand it smooth with 220- to 320-grit sandpaper.
In many cases, there is no need to apply any type of sealer or finish to furniture or other objects made from teak. Left unsealed, teak's soft, golden finish transforms into a silver-gray patina over time. If you don't want your teak to change color, applying sealer will help to preserve its original golden appearance.
Oil-based sealers and lacquers don't work well with teak unless the teak is treated with a special sealer prior to application. After applying a filler, if desired, brush on a vinyl sealer designed for use with teak and other oily woods. The vinyl acts as a barrier between the teak and the top coat of sealing, preventing problems with peeling and improving adhesion. After the vinyl dries, use a brush or rag to apply your lacquer or oil-based sealer. Don't use water-based sealers with vinyl, as they don't bond well together.
If you don't want to work with the harsh chemicals used in many oil-based sealers, you can find water-based products designed specifically for sealing teak. These products can be used with or without fillers, depending on the desired surface finish and texture. After cleaning the teak with a product designed for teak wood, apply water-based teak sealers with a clean, lint-free cloth. Plan to reapply at least once a year to maintain a protective seal and prevent the teak from changing color.