(image via: Miscpix)

Buying a hot beverage can be a maddening experience. At first it’s way too hot to drink, and then it cools down so quickly that you don’t have a chance to drink it before it’s tepid and unappealing. The same thing happened to German researchers Klaus Sedlbauer and Herbert Sinnesbichler: while walking around an outdoor Bavarian Christmas market, they noticed that their mulled cider was never at optimal drinking temperature. So rather than complain like the rest of us, they set out to find a solution.

That solution is phase change material (PCM). PCM is a wax-like substance that’s already used in construction and clothing because of its remarkable temperature-regulating capabilities. Sedlbauer and Sinnesbichler reasoned that they could put PCM to work keeping beverages at their ideal drinking temperature, whether that’s hot or cold.

PCM is able to absorb and maintain heat or cold for long periods of time. It melts when warmed and solidifies when cooled. Different PCMs have different melting points. If a hollow-framed mug were filled with PCM that becomes liquid at exactly 136.4 degrees Fahrenheit (the ideal drinking temperature for warm beverages) and the mug’s reservoir filled with a warm beverage, the PCM would absorb excess heat, bringing the liquid down to drinking temperature and keeping it there long enough for you to enjoy your coffee. It works for cold drinks, as well, but that would require buying a different mug for different temperatures: one for hot, one for cold and one for icy. The researchers are currently shopping their idea around and believe it may be on the market by the end of 2009.