Brew strainer
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The brew strainer allows you to prepare tea directly in a thermos. To do this, you just need to pour the tea leaves into the strainer and fill the thermos with boiling water. The tea strainer is a fine mesh, most often metal, that holds the tea leaves, preventing it from falling into the spill. Thanks to him, the purity and hygiene of the thermos, as well as the tea itself, increases. There are various options for the brew strainer. Often the sieve is simply built into the neck. In this case, the strainer acts as a coarse filter. Many thermoses have a strainer in the form of an elongated cylinder, with a deep immersion in boiling water. There are also other designs of the custard strainer.
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French press. A thermos with a French press allows you to brew natural ground coffee directly in a thermos. The French press itself is represented by a disc filter, which is pressed against the handle. When pressing on the handle, the disc filter presses the tea leaves to the bottom, thereby filtering out large coffee ground particles. The basis of the disc filter is a metal mesh. Under the grid it is recommended to put a special filter paper. Disposable paper filters are inexpensive. A French press performs two functions at once: pressing and filtering. The French press removes the bitterness of phenolic resin from coffee, which makes the coffee softer and more pleasant than ever.
Capacity
The nominal volume of a thermos is the maximum amount of contents that it can be guaranteed to contain.
This parameter is directly related to the type (see above). So, a capacity
of up to 500 mL is quite normal for a thermo mug, a flask or a baby thermos, but it is considered small for a classic thermos, and even more so a jug or a thermos for food. The
"500 to 1000 mL" category includes most traditional and food models; for mugs, flasks and children's thermoses, this is actually the maximum volume. Among the jugs there are many more capacious options —
from 1000 to 1500 mL. A volume
of 1500 to 2000 mL is considered quite large, and the most solid models can hold
more than 2 liters.
Anyway, a large volume allows you to hold more drink or food, but the downside of this is an increase in the size, weight and price of the thermos itself. Therefore, when choosing, you should not chase the maximum capacity, but proceed from real needs. For example, a model of 400 – 500 mL is quite enough for two cups of coffee, and for tea drinking at a halt for 3 – 4 people, it is advisable to have a model of at least 1000 mL. More detailed selection recommendations can be found in special sources; especially they will be useful to those who choose a thermos for long-distance hiking trips.
Opening/supply
The type of main cover provided in a thermos. The main cover in this case is a device that directly covers the working volume of the vessel; an additional cap can be installed on top of it, which often also plays the role of a cup. In modern thermoses there are the following types of main lids:
screw-on (screw),
valve,
cover,
hinged cover,
drinking cover,
pump (pump),
stopper. Here are the features of each of them.
- Screws on (screw). Solid (without holes) screw-on cover, secured with a thread. Such lids are very simple and at the same time reliable, but you cannot drink or drain the contents through the classic screw - you have to remove it completely. There is also a more advanced design that allows you to drain the contents without removing the screw - just partially unscrew it; however, this is a rather specific option that is not used often. Be that as it may, twists are found mainly among classic and food thermoses (see “Type”), for which the mentioned nuances are not decisive.
- Valve. A cover (most often threaded) equipped with a valve through which the liquid contents of the thermos can freely flow. Such lids are more complex and more expensive than “blind” screws (see above), but to access the contents you d
...on’t need to unscrew the screw every time, just open the valve. This not only provides additional convenience, but also reduces heat loss. Thanks to these advantages, valves are extremely popular in classic thermos flasks; they are also often used in thermal mugs (see “Type”). The disadvantages of this option include the fact that the valve opening is usually made quite narrow and is easily clogged with impurities (for example, tea leaves or coffee grounds). Therefore, the valve can only be used for liquids without such impurities (this also applies to food thermoses, which can also be equipped with valves). However, there are models with two different valves included, for drinks of different consistencies and aromas.
- Lid. Lids in this case are devices that do not have threads (unlike the screws described above) and are held in place solely by friction or a latch. The design of the lids can be different: some cover the neck from the outside, others are pressed inward when closing; There are also more specific options. In any case, the lids are easy to remove and put back on, but they are not very reliable - for example, it is not recommended to turn such vessels over. Therefore, this option is found mainly in thermal mugs and thermoses for food (see “Type”), for which the mentioned disadvantages are not critical.
— Hinged cover. A variation of the lids described above, which, when opened, is not removed entirely, but is folded to the side on a special mount. Thanks to this, the likelihood of loss is reduced: in fact, you can only lose the cover along with the thermos itself; and a latch, spring, or other similar device is usually provided to hold the cover in the open position. On the other hand, mount somewhat affects the price and dimensions of the vessel. This drawback is least critical for flasks and mugs (see “Type”), and it is among these types that hinged lids are most often found.
— Cover-drinker. Lid (regular or threaded), complemented by a special hole for drinking. This design allows you to drink from the vessel without removing the cover; and during “non-working” hours the hole is covered with a flap or other similar device. Drinking lids are extremely popular in thermal mugs and auto mugs (see “Type”): they allow you to drink from the mug comfortably while at the same time minimizing heat loss and the likelihood of spilling the contents.
— Pump (pump). Lid (classic or threaded) with built-in pump. Most often, this pump is activated by a special button: when you press this button, a portion of liquid comes out of the spout, and the thermos does not need to be tilted. However, such devices are quite complex and cumbersome, so it makes sense to use them only in thermos jugs (see “Type”): the size and weight of the pump is small compared to the dimensions of the jug itself, and tilting such a thermos can be difficult - it’s easier to use a pump.
- Cork. A classic stopper that fits tightly into the neck of a thermos and is held in it without threads or other similar devices. Corks differ from the lids described above in their greater thickness, and also in that they are inserted into the neck from the inside (while the cover can cover the vessel from the outside). Plugs are very easy to use, but have low reliability, which decreases even more as they wear out. As a result, this option has practically fallen out of use.Material
The material from which the body is made is the outer part of the thermos, inside of which the flask is placed.
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Plastic. One of the main advantages of this material is its low cost. In addition, it can be given any colour, and low thermal conductivity contributes to better temperature retention. On the other hand, plastic cases are noticeably inferior to steel cases in terms of strength and reliability, and scratches easily appear on their surface, due to which the product loses its presentation as it wears out. Therefore, plastic is used mainly in inexpensive models of thermoses.
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Stainless steel. Steel is somewhat more expensive than plastic, but much stronger and more reliable. In addition, the steel surface has a stylish appearance that is long-lasting thanks to its scratch resistance. Among the shortcomings of this material, in addition to the price, high thermal conductivity can be noted; manufacturers usually compensate for this moment with various tricks that further increase the price. Nevertheless, in general, steel is a very favorable material in terms of price and quality, and it is from it that the cases in most modern thermoses are made.
Carrying handle
The special
handle for convenience of carrying of a thermos. The design of such a handle can be different: for example, in ordinary thermoses and thermo mugs (see "Type") it is usually installed on the side, in food thermoses and jugs — from above (and is made collapsible). The handle can be a structural element of both the thermos itself and its cover (see below). In addition, the small carrying strap that some models are equipped with is also considered a handle in this case (but the shoulder strap does not count, see below).
Anyway, holding a thermos by the handle is usually more convenient and safer than by the smooth body, especially when it comes to a large-capacity model.
Case
The presence
of a cover in the scope of delivery of a thermos. The cover performs two main functions: it protects the case from dirt and scratches, and also slightly improves thermal insulation. In addition, additional equipment — handles, straps, etc. — in some models is placed on the cover.
Note that the case can be bought separately or even made by yourself, but it is most convenient to purchase a thermos immediately equipped with a case.
