2002-06-10 – Adaptive materials
The half-insulated mug

When drinking tea, I like it to cool off quite a lot before I even touch it – too many memories of burnt tongues as a kid, I guess! So, I sit the cup down, and leave it a while, then start drinking it. Needless to say, it is then reduced in volume, and has already cooled quite a bit, so it then gets cold too fast!
The worst thing to do is put your tea in an insulated mug, however, since this just keeps the tea red hot until two hours later, and, like most people, tea is an impulse thing, rather than a planned event! Even then, you are likely to still burn your tongue.
The solution would be a mug designed to allow the liquid to cool, then stop it from cooling too rapidly. You could get very technical, using space age materials and powered systems, which would be very expensive, but very neat.
I envisage a simpler idea, however, which is to literally half insulate a mug. The top part is like a standard mug, but about a third of the way down, it becomes a double skinned container. Due to convection, the top layer will always be warmest, so the warm liquid at the top cools, due to conduction from the un-insulated part, while once the drink is down 1/3 of the way, this loss is suddenly limited to only the surface of the drink, which lowers the rate of cooling, keeping your beverage at the ideal temperature for the drinker, for longer!
An additional advantage is that the thin top part will still feel like a normal cup to our lips, unlike a bulky double walled insulated mug! Brilliant!

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