Dampen the teak furniture thoroughly with a garden hose. If it is outdoor furniture, remove all dirt and debris.
Clean your teak furniture with teak cleaner. This is a specialized cleanser available at marine or furniture stores. SEMCO recommends wearing goggles and gloves while using teak cleaner. Teak cleaner is often available in two parts, or two different cleaners. Work in sections to apply the cleaner.
Apply the first cleaner to one area of the furniture, then scrub it with a soft-bristled brush. Rinse the area of all cleaner. Apply the second cleaner and scrub it, then rinse again. Finish the rest of the teak furniture in this fashion. Do not allow the cleaner to dry on the furniture. After cleaning, allow the furniture to completely dry.
Apply a teak sealer to the teak furniture. Use a foam brush to apply the sealer to the wood. Use generous amounts of sealer--the wood will absorb it.
Apply a second coat of sealer for maximum protection. SEMCO recommends applying the second coat on the same day as the first. Begin applying the second coat after the first coat is done, starting in the same area as you did the first time. After the second coat is finished, gently wipe off excess sealer with a clean cloth. Allow the furniture to dry completely before use.
Preserve the life of your teak wood by applying teak sealer to the furniture every six months to a year, as recommended by Teak Warehouse. Do not use a teak cleaner on it before every sealer application, unless you wish to remove the previous coats of sealer. Instead, clean the furniture with soapy water.