How to Remove Tea Stains from a Teapot and Cup

The group of compounds that cause stains in tea is called tannins. Tannins dissolve in water and pass into the tea as it steeps, but when they meet air and minerals on the surfaces of containers, they oxidize and leave a dark buildup that does not dissolve in water. This buildup forms a thin, even film on the inside of a cup, at the bottom of a teapot, and on its strainer. It is not a greasy stain; it does not feel slippery to the touch. It is a chemical deposit, not dirt, and that distinction directly determines which cleaner will work.

Dish soap is designed to separate grease from water; that is exactly what its molecules do. Since there is no grease to dissolve in a tannin deposit, the soap slides off the surface and the stain remains. Scrubbing does not help either, because the film is firmly attached to the surface of porous porcelain and steel. At this point, many people either accept the stain or risk scratching the cup by using a steel-wool scrubber. The solution, however, is not abrasion but loosening the film with an alkaline environment. For the same reason, a tea stain can remain inside a cup after it comes out of the dishwasher.

Baking soda is both inexpensive and suitable for this job. Put one 5 ml measure of baking soda in the cup or teapot, add hot water, and let it sit for a while; then wipe it with a soft sponge and rinse thoroughly. For stubborn stains, mix baking soda with a little water to make a paste and apply it directly to the stain. Soaking takes the place of scrubbing: the longer it sits, the less force you need to apply by hand. Rinsing afterward is important because leftover baking soda can leave a faint taste in the next cup of tea and affect its flavor.

The material of the container changes the method slightly. Porcelain and glass tolerate baking soda without a problem. The same method works on stainless-steel teapots, but the inside surface of the steel is more prone to scratching, so spread the paste with a cloth, not a steel-wool scrubber. The lower pot and the strainer are the spots most often missed; deposits there slow the flow of tea and affect brewing. On teapots with wooden handles or painted surfaces, do not let baking-soda water touch the handle; apply it only to the inside surface. In glass teapots, stains are noticed earliest because the film is immediately visible when held up to the light.

Preventing stains is easier than cleaning them and comes down to one habit. The teapot should be emptied, rinsed, and dried each day; tea left inside overnight can thicken the film in a day. Do not leave cups on the counter with tea still in them either. Tea brewed with hard water develops deposits faster because the minerals in the water combine with tannins to form a tougher film. With hard water, using a filter before boiling or cleaning more often helps balance things out.