(1) If the teacup is used for a long time, it will leave brown tea stains. You can wipe it hard with a wet soft cloth dipped in soot, and the tea dirt can be removed.

(2) The dirt on the inner wall of the teacup cannot be cleaned with cold water. You can pour strong salt water into the cup, then drop a little vinegar, leave it overnight and scrub it the next day, so it is easy to remove the dirt.

(3) If there is tea dirt in the cup, pour a small amount of citric acid into the cup, and then add hot water to dissolve the citric acid. After soaking for a few minutes, the tea stains can be wiped off with a cloth. It is also effective to cut the edible lemon and scrub or clean it with a drink rich in citric acid. Citric acid is an organic acid, which can be obtained from many fruit juices (especially lemon juice) and is harmless to human body.

(4) Stainless steel utensils, if there is scale composed of hard water, can be cleaned with vinegar.