The best thermoses in preserving temperature and how do they keep the coffee hot?

We are all seeking for the best thermoses to use to serve drinks without discomforts, especially after the spreading of the imitated-bad thermoses which leak temperature quickly, while we want to keep it hot for the longest time, so we have prepared this guide to help you purchasing thermoses and keeping your coffee hot for the longest time.


How does thermos work to preserve the temperature?

  • Thermos is an Insulated container that can keep the temperature of the drink whether hot or cold, that’s because it is working on reducing heat transfer to keep the temperature of the drink for the longest time, the “thermos” word is derived from the Greek word “thérmē” which means heat.
  • Tea and coffee thermoses are based on vacuum insulation technology, it consists of Inner & outer walls, and the vacuum space between them to prevent the temperature from transferring out, the two walls are connected at the thermos neck.
  • The inner wall is made from insulating and poor heat conduction materials, but these materials usually transfer the temperature slowly, so we use vacuum insulation technology which includes covering the inner wall with a silver layer to prevent the heat transfer via radiation, and the vacuum between the inner and outer wall prevents from temperature transfer via the convection.
  • The inner and outer walls were made to be skinny, to reduce the temperature from entry or exit, the outer cover provides additional insulation, thus the hot drinks keep hot and the cold keep cold for the longest time.
  • Rose Thermos | How does thermos work

Invention Story of the thermoses and how did it develop?

Rose Thermos | Scottish scientist Sir James Dewar

  • The invention of the thermos has started with the Dewar flask, which invented by Scottish scientist Sir James Dewar to keep the temperature of the chemical materials constant while conducting experiments, he put a glass flask inside another larger glass flask, and make the space between them vacuum to keep the temperature of what's inside the smaller bottle, but he didn’t register a patent and make his invent a gift for the scientific community.
  • Renold burgher developed Dewar’s flask and manufactured the thermos commercially in a miniature model to use in homes.
  • In 1906 American businessman William P. Walkers met Renold burgher, then he started to sell the thermos product in the USA, after that, he increased the capital necessary to manufacture, import machinery, and train workers while demand quantities have exceeded production in the United States.
  • Soon after the use of vacuum insulation technology was developed, and gained more importance during the Second World War, until the manufacturer started exporting vacuum flasks to more than 100 different companies around the world.

Thermoses manufacturing was developed last years, and now there are a lot of thermoses types and shapes, which can keep the temperature for a longer time, but also there are imitated & bad thermoses, so this makes it difficult to recognize the copied thermoses from the original ones, so you must learn about the types of tea thermoses and how to check it before purchasing, there are also a lot of coffee thermoses “Dallah” types, and you can choose the best to purchase.

The best thermoses in preserving the temperature

  • Some of the German thermoses have a high ability to preserve the temperature of the drinks, but its designs are old-fashioned and not suitable for hospitality purposes.
  • Most Japanese thermoses are good, but they don't have originality and they do not offer luxury hospitality options 
  • Chinese thermoses are good also but you should ensure getting the original & well-known branded thermos to have your Arabic coffee in a safe & healthy thermos.

We can also segment thermoses based on the inner 

But in general, there are specification should be available in the thermos such as:

  • Good appearance Indicates the good quality materials, the thermos is made from.
  • The pink color of the glass in the inner glass thermos.
  • There are no black points inside the thermos because it may mean the use of asbestos which may cause cancer.
  • All parts of the thermos must be cohesive.
  • Ideal weight, as the lightweight thermos can’t reserve heat well.

How to test the thermos at home before you use it?

Rose Thermos | How to test the thermos

You can test the thermos to ensure the allegations of the seller or the manufacturers, this through doing separate experiments, each one has these steps:

  • Put the boiled water in the thermos and measure the water temperature by centennial Kitchen Thermometer, then seal the thermos cap tightly.
  • Open the thermos cap and measure temperature after many hours, and record the temperature.
  • Do the experiment again with the same steps, by increasing the hours before you measure, you can also do this experiment many times by raising the number of hours.


You must use the water not coffee in these experiments as if you use coffee that makes it difficult to replace it in the event that you find any thermos defects, you must also shake the thermos before measuring left and right to ensure removing any thermal layers which make us measure correctly.

The Reasons that make thermos lose its temperature

  • The type of the thermos: It is the most important one, so you must ensure using original thermoses, you can recognize it by the tips which you can find in the link: how can you recognize the original thermos.
  • How to use thermos: you may use the thermos in the wrong way.
  • You must also give attention to close the thermos cap tightly after pouring as the thermos may lose its temperature if you don’t close it well, here we mention that press cap thermos or thermoses are doing best, but we can’t clean it well because of difficulty of getting to the inner parts, so the accumulated bacteria may harm our health.

How to keep your thermos hot?

  • Choose an original & healthy thermos to keep your drink hot without reacting with it, even if it costs you more, as the thermoses prices are affected by a number of factors
  • Use the thermos in the correct way.
  • Close the thermos cap well so as not to lose the heat of the coffee for the longest time.


  • Thermoses are based on vacuum insulation technology, it consists of Inner & outer walls, and vacuum space between them to prevent the temperature from transferring, covering the inner wall with a silver layer to prevent the heat transfer from inside to outside and back.
  • Thermos began as a device that was used in chemical laboratories and then developed until it was possible to use at homes in a miniature model, which we use also in travels and journeys.
  • Thermoses manufacturing was developed last year, and now there are a lot of thermos types and shapes in markets, so you must ensure purchasing the originals which can keep the heat for the longest time to enjoy coffee.
  • Don't be fooled by the cheap prices of some thermoses, you can learn more about the prices of the thermoses within the previous link, you must also ensure its manufacturing to don’t cause Financial damage or health harms caused by the carcinogenic asbestos.
  • You can test your thermos at home before using it.
  • You must ensure using the thermos in a correct way and clean your thermos well to keep the temperature & taste of your drink, espacially after using to keep Saudi Coffee which contains spices, used to prepare Arabic Coffee.