Tea contains compounds, known as tannins, that naturally tan or stain surfaces. Tea staining can occur in various situations; not only on the inside of stainless steel teapots or other cookware, but also on stainless steel utensils such as tea balls and teaspoons, and larger surfaces such as tabletops. As tea stains only the surface of stainless steel, the removal of the stains typically requires only the use of a mild acid or slightly abrasive cleaning tool to break up the stain for quick removal.
Fill your teapot or other cookware with undiluted distilled white vinegar.
Heat the vinegar until it boils, set the teapot or cookware aside to cool and then pour out the vinegar. If you're cleaning tea stains on an unpolished stainless steel tabletop or other large item, skip this step.
Rub the stainless steel with a damp non-abrasive scrubbing pad or fine-grade brass wool in the direction of the surface grain to remove the tea stains. If you're dealing with a tough stain, sprinkle baking soda or pumice on the stain and scrub, using light pressure, to wear away the stain.
Rinse your stainless steel item thoroughly with warm water when finished. If you're cleaning a tabletop or other large surface, wipe it with damp, soft, lint-free, microfiber cloths.
Wipe the stainless steel dry with cloths to prevent spotting.
Polished Stainless Steel
Fill a spray bottle with distilled white vinegar. If you plan to use a commercial stainless steel cleaner, skip this step.
Cover the entire stain with vinegar or commercial cleaner. Wait 15 to 20 minutes or for a timeframe recommended by the manufacturer of the cleaner. If you're cleaning stainless steel utensils, boil the utensils in a pot of white vinegar, set the pot aside to cool and then pour out the vinegar.
Rub the stainless steel with a cloth to remove the vinegar or cleaner and buff away the stain.
Rinse the surface with warm water or warm, damp cloths. If you used a commercial cleaner, wash the stainless steel with a warm, soapy cloth and then rinse with warm water or damp cloths.
Dry the polished stainless steel thoroughly with soft cloths to shine it.