If there is an odor after opening or using the tumbler:
Pour boiling water with vinegar, citric acid, or baking soda into the tumbler and let it cool completely.
Rinse thoroughly and check if the odor is gone.
Note: Do not soak the entire tumbler in the solution, as vinegar or citric acid may cause discoloration of the exterior.
There is no specific concentration, a guideline is 1 teaspoon per 200 ml of hot water.
To remove rust inside the tumbler:
Pour boiling water with vinegar or citric acid into the tumbler and let it cool completely.
Rinse thoroughly and wash the tumbler with dish soap.
Note: Do not soak the entire tumbler in the solution, as vinegar or citric acid may cause discoloration of the exterior.
There is no specific concentration, a guideline is 1 teaspoon per 200 ml of hot water.
To remove stains (like tea stains) inside the tumbler:
1.Fill the tumbler with hot or warm water, and add a heaping teaspoon of baking soda or oxygen bleach.
(Be cautious, as oxygen bleach may cause spills.)
2.Let it sit until the water cools completely.
3.Discard the solution, then rinse thoroughly.
4.Wash with dish soap, rinse again, and dry.
Note: Do not close the lid during soaking or cleaning, as the increase in air pressure could be dangerous.