Put on rubber gloves to protect your skin from the ammonia. Pour two cups of ammonia into a large bucket, and add one capful of laundry detergent. Plunge the scrub brush into the solution and swirl it to mix the ingredients.
Working in one-foot by one-foot sections, use light pressure to gently scrub the weather-damaged teak table with the ammonia and detergent solution. When the entire table, top and bottom, has been scrubbed down, hose it off thoroughly with a garden hose. Dispose of any unused cleaning solution.
Let the table dry completely, preferably for at least three days.
Pour teak oil onto a rag and gently rub it into the wood in the direction of the grain. Start at the top of the table and work your way down to the bottom of the legs. Coat the entire table with the oil, top and bottom, and allow it to dry completely before using.