Apply an oil-based soap, such as a gentle laundry detergent, to one side of your teak bowl. Avoid anything with perfumes or dyes. Massage the soap all over the chosen side of the bowl and let sit for five minutes.
Massage the soap further against the bowl using the soft-bristled brush. Rinse with clean water. Dry thoroughly with a soft cloth.
Assess the difference between the cleaned and uncleaned sides of the bowl to determine whether you require more thorough cleaning. Repeat steps 1 and 2 for the other side of the bowl.
Select an acidic cleanser, formulated for teak, if you wish to recreate the look of the bowl when new. Choose a one-part solution, made with oxalic acid, for a gentler approach. Use a two-part hydrochloric acid formula only if you require an even more powerful cleaner.
Put on gloves before opening any of the heavy-duty cleansers. Apply the acid-based cleanser to a small area on the bottom of the bowl with a nylon brush, following the manufacturer's instructions. Gently scrub the cleaner using a bronze wool pad, but not steel wool. Rinse with clean water.
Apply the second part of the solution if using a two-part cleaner. Keep your gloves on throughout. Cover all areas where you applied the first solution. Do not skip over any areas or the second solution will not neutralize the acidic first solution and may damage the bowl.
Select a teak oil, either linseed for a darker finish or tung oil for a more water-resistant finish, although at a higher price. Select a specially formulated teak oil with UV filters and mildew retardants if you keep the bowl in direct sunlight or in a damp location.
Apply the teak oil to your bowl with a soft-bristled paint brush. Wipe up any drips in the oil immediately with a soft cloth. Add second, third and even fourth coats of oil until you are happy with the finish.
Stop adding coats when the wood ceases to "drink up" the oil. Wipe the entire bowl with the cloth until it is uniformly matte. Let the bowl dry completely before handling it or filling it with anything. It should not be oily to the touch.
Ensure the bowl is in pristine condition before sealing. Clean and oil any bowl that is not brand-new. Wipe off any excess oil completely so the bowl isn't oily to the touch.
Wait at least two weeks after oiling the bowl before you seal it. Rinse it with water after the two weeks. Let the bowl dry completely.
Apply the sealer to your teak bowl with the soft-bristle paintbrush. Wipe away any excess sealer immediately with a cloth. Paint on two or three coats until the finish appears uniform.