Like a lot of great inventions over the past 200 years, the Vacuum Flask was also invented by a Scotsman! In-fact, for a short while before “Thermos” got involved, (more on this later), it was known as the Dewar Flask, named after the man himself, Sir James Dewar. James was born in 1842 in Kincardine-on-Forth, Scotland and was a chemist and physicist whose study of low-temperature phenomena lead to the design of the first double-walled vacuum flask in 1892. Below is a picture of James’s original Vacuum Flask;


So what exactly is a Vacuum Flask? Put simply, it’s an insulating storage vessel that greatly lengthens the time over which its contents remain hotter or cooler than the flask’s surroundings. It normally consists of two flasks, placed one within the other and joined at the neck. The gap between the two flasks is partially evacuated of air, creating a near-vacuum which significantly reduces heat transfer by conduction or convection. The design of (what was then known as) the Dewar Flask was so effective that it remains much the same today, as when it was invented over 100 years ago.

Dewar’s design was quickly transformed into a commercial item in 1904 as two German glassblowers, Reinhold Burger and Albert Aschenbrenner, discovered that it could be used to keep cold drinks cold and warm drinks warm. The Dewar flask design had never been patented but the German men who discovered the commercial use for the product renamed it “Thermos”, and subsequently claimed both the rights to the commercial product and the trademark to the name. This left Dewar somewhat short-changed and slightly undervalued in the history books…


As time went on, “Thermos” products, known almost universally now, had been used for insulin transport, as well as being utilised in various instruments measuring electric power, rate of climb in aeroplanes, detection of oil deposits, weather reporting and much more!

Later, the Thermos Coffee Butler was successfully introduced onto the market. A vacuum-insulated glass carafe, becoming one of the top household products in North America that year. This product evolved into stainless steel variants and could be found in the majority of family homes across the continent!


It wasn’t until the late 60’s and early 70’s that “Thermos” really started producing the sort of products that we associate them with today. The classic “Thermos Flask”. A product that lives in the back of a kitchen cupboard in almost everyone’s home!


These household flasks have been through many minor design changes over the 50 years that they have been in production. But fundamentally they all do exactly the same job, in exactly the same way. Below, shows the most recent iteration of the “Thermos” design language;


In summary, I really enjoyed reading about and researching the “Thermos” brand and the history behind the invention of the Vacuum Flask. But what I really took away from this is how surprisingly, the core of the product hasn’t really changed much in over 100 years! Is this a good example where “if it ain’t broke, don’t fix it”? Yes, the current “Thermos” products look very nice and shiny, but they do exactly the same job and are probably not that much better at it. So what is next for “Thermos”? Are there anymore applications where the patented Vacuum Flask technology can be used? Alternatively, what is the next scientific discovery waiting to be commercialised?

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