How To Clean Teak Outdoor Furniture
If your teak furniture requires cleaning, use a normal household bristle brush (not too hard) and some warm, mildly soapy water. Rinse with clean water. Proprietary cleaners are available that will clean various deposits and accumulated dirt and stains. Do not use high-pressure hoses, and do not use steel wool or steel wire brushes since any residue from the brush left in the grain will rust and discolor the wood. If the furniture has some stubborn, heavily ingrained stains, you can remove these by sanding with a fine grade of sandpaper, being sure to work only with the direction of the timber grain.
Naturally occurring oils that saturate teak wood are its blessing and, if improperly cared for, its curse. Teak is used for outdoor products because of these oils, which impart an attractive appearance and, more importantly, inhibit the tendency to rot. However, the sun brings the natural oils to the surface, where they dry to a discolored gray, ultimately becoming black due to the mold and mildew that tend to feed off the oil.
So, be good to your teak outdoor furniture; and it will return the favor!