If you can buy scale cleaning agent, just buy a pack. Use a packet of scale cleaner to tear it open and pour it into the container, inject hot water, and soak the inner wall of the container fully in water. After 30 minutes, the scale can quickly fall off and then clean it with clean water. If the dirt is particularly stubborn, soak it for a longer time.

If you have not purchased scale cleaning agent, there are the following methods to remove scale:

1. Put some paper scraps in the bottle, then pour in warm salt water, shake it for a while, and the scale will be removed.

2. You can pour about 500 grams of baking soda with a concentration of 1%, or heat the vinegar and put it in a bottle, shake it gently, and the scale can be removed.

3. Slightly break the two egg shells, put them into the bottle, then put them in a half tea jar of cold water, plug the bottle plug and hold it with one hand, hold the neck of the bottle with your thumb and other fingers, hold the bottom of the bottle with the other hand, rotate up and down, left and right. For about 20 seconds, remove the bottle plug, pour out the eggshell, and wash it twice with clean water.

4. Use 250 grams of vinegar, heat it and pour it into a hot water bottle, soak it for a few hours, then shake it up and down, left and right, and the scale in the bottle will fall off.

5. Take 200 grams of dilute hydrochloric acid and soak it in the bottle for a while, then shake it to remove the scale in the bottle.

6. Pour the water from cooking noodles into the bottle, shake it for a few minutes and pour it out, then rinse it with clean water.

7. Take some sunny leaves or pumpkin leaves and cut them into pieces of 3 cm to 4 cm square, put them into the bottle, add a little cold water, gently shake the thermos bottle for a few times, pour out and wash with clean water.