How to open a thermos that is tightly twisted

Thermoses today are gaining great popularity, becoming an indispensable attribute in almost every family.

But it happens that the cap of the thermos turned out to be tightly screwed and it becomes almost impossible to open it. What needs to be done to solve this problem will be considered in the article.

The reasons

The reason that the thermos (thermomug) is tightly screwed on the lid is a decrease in pressure inside it. Due to this difference, it becomes very difficult to open it. To solve the problem, it is necessary to press the valve in the cover to equalize the pressure and calmly open it.

At the moment when hot liquid is poured into the thermos, the metal thread expands and fits snugly to the base, a vacuum is formed. As a result, the lid is tightly attached to the thermos, and it becomes very difficult to open it.

How to open a thermos that is tightly twisted

In order to open a tightly closed thermos with hot contents, you must wait until the liquid has cooled. However, there are methods that can accelerate this process and help to quickly open a tightly twisted plug.

Opening Methods

Safe and effective methods for opening the lid are to cool or heat the lid. Using an opener or knife can also help solve this problem, but it can damage the thermos.

The first method (under cold water)

This method is suitable for a thermos flask with an external thread. The essence of the method is to place a thermos under cold water for cooling. So the metal thread will begin to narrow, less closely fitting to the flask, and it will become much easier to unscrew the lid.

The second method (under hot water)

Thermoses with a cap with internal thread must be placed under hot water. During heating, it will expand and fit less tightly in the main part of the thermos.

We use physical force

Using physical force, you can also open a tightly twisted plug. The best way to do this is to pull the cover up.

We use an opener

If the cork is flat, you can try to pry it with an opener. This will break the vacuum that has formed inside the thermos and allow you to easily unscrew it.

Important! Use this method very carefully so as not to damage the integrity of the dishes.

Special devices

You can also independently make a special device for opening threaded covers. To do this, you need the following materials:

  • elastic;
  • fine sandpaper;
  • long bolt with nut;
  • two wooden planks 20-25 centimeters long.

To begin with, it is necessary to make through holes in the strips of such a diameter so that a bolt can be easily inserted into it.

Next, glue sandpaper strips onto the strips and thread the bolt through the holes, securing it with a nut. In this case, the emery strips should remain inside the device, and connect the free edges of the strips with an elastic band.

Using such a device is quite simple: you need to adjust the size of the opener to the diameter of the lid with a nut. Put on the structure and gently turn. Sandpaper provides a tight grip with a metal cover, which greatly facilitates the process of loosening.

Other methods

There are several additional ways to open a thermos:

  1. Wrap the cover with electrical tape and pull it strongly in the direction of thread movement;
  2. Use leather gloves during opening (the code fits snugly against the metal without causing slipping);
  3. Knock on the lid and walls;
  4. Try to pry with a knife, so the vacuum inside is broken, and it will be easier to open the thermos.


There are many different ways to open a tightly screwed thermos lid. All of them are based on the properties of the metal (narrowing during cooling and expansion with increasing temperature), as well as a violation of the vacuum. When choosing any of the possible methods, you should be careful not to damage the thermos.

Watch the video: Revomax Vacuum Insulated Flask with Twist-Free Cap Review (November 2019).


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