Remove tea stains without damaging the cup
A brown line inside a cup calls for ordinary care first. The right method depends on the cup's surface, not just the colour of the stain.
Start with the surface
A glazed ceramic mug, an enamelled cup and a coated travel tumbler are not interchangeable cleaning projects. Before reaching for a stain-removal trick, check the material and the maker's care instructions. Empty the cup, wash it with the permitted everyday method and inspect it in good light. A brown tea line is not the same thing as a crack, chipped glaze or a peeling coating. If the surface itself is damaged, making the colour disappear will not repair it. Do not use a sharp tool to scratch away a mark or a rough pad that changes the finish of the drinking surface.
A pale cup makes staining more noticeable, which can make an ordinary deposit feel more alarming than the same residue in a dark vessel. That is a reason to clean and inspect both regularly, not to judge cleanliness by colour alone. A dark cup can also hold residue around the rim and handle attachment.
Choose one compatible method
If normal washing leaves a mark, look for a stain-treatment method specifically allowed for that material. Follow its amounts and contact time rather than combining several internet remedies in the same cup. A technique suitable for plain glazed ceramic may damage decoration, metal trim or a special coating. Use only cleaning products intended for the relevant food-contact equipment, rinse thoroughly and let the cup dry. If the maker gives no suitable method and the mark concerns you, ask for advice. There is little value in removing a cosmetic stain at the expense of the surface that makes the cup usable.
Make the next clean easier
Empty tea when you are finished instead of letting a small puddle dry into a dark ring. Rinse or wash the cup at a convenient point in your normal routine, paying attention to the lip as well as the bottom. Keep a soft cleaning tool that reaches the inside without forcing your hand into a narrow opening. If the cup is difficult to clean every day, a simpler shape may be a better daily choice. Good care should preserve the vessel and leave it ready for another drink, without an escalating effort to make every used object look untouched.
