The history of the invention of a thermos begins in the 19th century and is associated with the name of the English inventor James Dewar Devard. But his goal was not to invent a container to retain the heat of hot liquids. Its purpose was a device for storing
rarefied gases. After some time, his student and follower R. Burger found a niche for commercial use of this invention. Soon his company gained great popularity and was engaged in nothing more than the production and sale of thermoses.
Modern thermoses for tea, which we find everywhere, are no different from the initial invention. And, as before, they are a glass or metal flask placed in a housing. Despite the fact that this invention is very simple in nature, it has been used in people's lives for a fairly long period of time.
Choose a thermos
If a thermos for tea is to be actively used in various kinds of trips, hikes or travels, then for these purposes it is better to choose with a metal flask. It is much stronger and can easily withstand active use for a long period. If you plan to use a thermos for tea in a domestic environment, then a glass flask is suitable. Despite the fact that it is more fragile and vulnerable to mechanical stress, it is nevertheless more practical from a hygienic point of view. At the same time, both a metal flask and a glass one cope equally well with their main function.
It is believed that thermoses for tea in a plastic case keep the temperature better. This may be due to lower thermal conductivity of plastic than metal. A good thermos for tea even after a day is able to maintain a temperature of 50 degrees.
Leak test
The choice of a thermos should be approached very carefully and responsibly. After all, this thing is purchased for long-term use, and not for one day. First of all, it is worth checking how well and tightly the cap is screwed. This is the main criterion that affects the conservation of fluid temperature.
Flask volume
Also, the duration of temperature storage depends on the volume of the flask. The larger the flask, the longer the temperature lasts.
Foreign odors
When choosing a thermos, it must be opened. It should not exude any unpleasant odors. If the aroma is present, then this indicates a low quality of the materials used for production. Using a thermos from poor-quality components can be harmful to your health.
When choosing a glass thermos, it should be shaken. The flask must be tightly fixed, otherwise sooner or later it will break. In this regard, a metal flask is much stronger, but during deformation, microcracks can form in it, which adversely affect the heat-insulating abilities due to a violation of tightness.
Gourmets and connoisseurs recommend using thermoses with a glass flask for brewing and insisting . They know exactly how to make tea in a thermos. This allows you to preserve the delicate taste of the drink, which is especially cherished by lovers and regulars of tea ceremonies.
Testing in practice
The quality of the thermos can also be checked in practice. If available at the point of purchase, this will be the best way to evaluate this product. To do this, fill it with boiled water and leave for 15 minutes. If during this time the body heats up, then the thermos for tea is of poor quality. The liquid in it will cool off very quickly, and there is no sense in such an acquisition.
In today's market there is a huge selection of thermoses that can satisfy the needs of any person in terms of design and practicality.
Thermoses for food are also widespread. They have the appearance of pots and hold the temperature in the same way.
So, the best thermoses for tea should meet the following requirements:
1. Must not exude harsh, unpleasant odors.
2. The cap must seal the flask.
3. The larger the volume of the flask, the better the temperature is maintained.
4. A metal flask is more practical and more durable to use, while a glass one is more hygienic.
5. When filling with boiling water, the body of the thermos should not heat up.