Cleaning the Thermos – Here’s How!

Cleaning the Thermos – Here’s How!

The best tips to get every thermos clean again

If a delicious hot coffee, tea or cocoa is required on the go, thermos flasks made of stainless steel or with a glass insert are indispensable. They keep it hot for up to 24 hours and are a daily companion for many on the way to work, school or study. They also counteract the flood of paper cups and are an ecological benefit. You don’t have to worry about cleaning, because little tricks make it very easy. This is how every thermos can be cleaned properly!

The long way to the thermos

The thermos flask has its origins as early as the 19th century, when AF Weinhold and the Scot Sir James Dewar independently invented the first prototypes of the vacuum flask. Both used a very similar principle and used their vessels to control the temperature of chemical substances that they needed in their scientific experiments. It was only in 1903 that R. Burger recognized the commercial benefit of the invention and had the idea patented. That’s a good thing, because as a thermos, a term that is now protected by trademark law, the vacuum jug began its triumphant advance and is used every day in many households today.

How does a thermos actually work?

The basic principle of the thermos flask is a reduced thermal conductivity, so that the jug contents remain hot or cold. For this, an inner piston is separated from the outer shell by a vacuum. In addition, the inner part is usually also mirrored so that the heat is reflected. Today the inner piston can no longer only consist of mirrored glass, but also of unbreakable stainless steel. Additional coatings reduce the thermal conductivity again.

In general, stainless steel jugs are often lighter than products with a glass insert and are easier to clean because they are largely resistant to cleaning agents. Real pluses for travelers. But many modern thermos flasks made of glass are also more unbreakable and easy to clean. So here personal taste can be taken into account when making a decision.

Clean properly with home remedies

Specialized cleaning agents for vacuum jugs are a real niche product and accordingly costly. These are particularly worthwhile for branded products or very dirty jugs, where cleaning with home remedies no longer works. In a first step, however, it is sufficient to fall back on grandmother’s knowledge. The home remedies are gentle, inexpensive and often ensure clear surfaces without any tea or coffee residues.

There are still a few things to consider when cleaning. First of all, there is no need to clean a thermos every day. If this is used every day or every second, it is sufficient to rinse the jug with hot water after use. The vacuum jug should only be cleaned intensively every four to eight weeks in order to remove unsightly, remaining stains. In addition, it makes sense to use separate thermos flasks for coffee and tea. Because even after cleaning, a few flavors left behind can affect the drink.

When choosing the appropriate home remedy, it depends on the type of jug. Is it a stainless steel thermos or is there a glass insert inside? Is it provided with a special, perhaps sensitive, coating? First of all, stainless steel jugs are the least sensitive. Largely resistant to various forms of salt, surfactants and typical acids, all household remedies described below can be used for cleaning. Only the dishwasher can pose a danger to the stainless steel jugs.

The machine can only be used if the manufacturer expressly recommends cleaning. The problem is that with some vacuum jugs, especially cheap ones, water can penetrate between the outer jacket and the insulating layer and damage both the vacuum and the inner bulb. In both cases, the jug loses its thermal insulation properties. Therefore, the thermos should not be completely immersed in the water, even when hand washing, but only wiped off with a damp cloth. A microfiber cloth is particularly suitable for this.

Suggested reading:

Descaling Coffee Machines: Consistently Good Coffee Enjoyment

Descaling fully automatic coffee machines – the right way

Home remedies for cleaning coated thermos flasks

A coated thermos is the most sensitive of all variants. The coating is applied to the inside and significantly reduces the thermal conductivity, which means that the contents of the vacuum jug stay hot or cold for longer, depending on the starting temperature. However, the special layer poses a problem when cleaning, as acids, salts and mechanical stress can attack the coating. You should therefore use dishwasher tablets or, no joke, denture cleaners for cleaning. Fill the jug with hot water, add a tab or an effervescent tablet and let everything soak overnight. Then rinse with boiling water and the inside will shine again.

But be careful: although both are effective, they can leave an aftertaste. Therefore, before the next use, first fill with a little coffee or tea, swirl and throw it away.

Clean the glass thermos with household remedies?

You can treat a glass flask with a denture cleaner like a coated vacuum jug, but not with dishwasher tablets. These attack the glass layer and lead to milky streaks. On the other hand, mechanical cleaning aids are not a problem. And so the fine steel wool, which is actually used to clean pots and pans, can make the glass bulb shine again.

From baking powder to salt – home remedies for stainless steel jugs

Stainless steel jugs are particularly insensitive and can be cleaned with almost any cleaning method. The only thing that is not advisable is steel wool, because it leaves fine scratches. The thermos can also be treated with harder cleaning agents. These include baking soda, salt and vinegar essence, which give very good results.

Half fill the pot with hot water and add two to three teaspoons of baking soda, baking powder or salt to the pot and soak overnight. If there are limescale deposits in addition to coffee or tea stains, vinegar essence is the product of choice. Pour in a few squirts with a little hot water and let it steep for several hours, swirling occasionally. After removing the rinsing solution, rinse all thermos flasks with plenty of hot water so that no aftertaste is left behind.

Specialized cleaner for thermos

The trade has also developed a number of products specifically for vacuum jug cleaning. These are mainly various powders that are intended to gently clean the jugs of stains and odors without mechanical action. There are also mechanical cleaning aids to remove stubborn residues. On the one hand, there are particularly soft brushes that do not scratch a coated piston. These brushes can of course also be combined with the household remedies mentioned in order to be able to do without powder cleaners. On the other hand, cleaning pearls can be found on the Internet. Without the addition of other agents that can later influence the taste, these pearls only clean with water and mechanical abrasion. A very gentle and environmentally conscious variant, which can be used for stainless steel jugs and glass flasks. Caution is only advised for very sensitive coatings.

Conclusion: cleaning the thermos is easier than expected

  • A thermos should only be cleaned intensively every four to eight weeks if used daily.
  • It doesn’t always take expensive special cleaning agents to make such a jug shine again. Common home remedies give very good results.
  • Home remedies such as denture cleaners, dishwasher tablets, and vinegar essence can leave an aftertaste. Therefore always rinse really well.
  • The cleaning agent must be adapted to the material of the jug and any coating.

With these tips, every thermos, whether made of stainless steel or glass, can be cleaned gently, quickly and easily. So let’s get to the practical everyday helpers, because they (unfortunately) do not clean themselves!