Unless you're someone who drinks their coffee fast, you likely face a bit of a conundrum when it comes to temperature – either you start with it at the perfect temperature but end up with it getting too cold, or you end up with it cooling down to the perfect temperature by starting with it too hot. Two young entrepreneurs, however, have created a product that they claim quickly cools your hot coffee to the right temperature, but then holds it at that temperature twice as long as it would stay there otherwise. Their product is called Coffee Joulies.

Mechanical engineers Dave Petrillo and Dave Jackson grew up together in New Jersey, but have since ended up on opposite sides of the U.S. That hasn't stopped them from collaborating on the design of Coffee Joulies over the past nine months.

Each Joulie contains a proprietary non-toxic phase change material, sealed inside of a polished stainless steel shell. The product is placed in the bottom a coffee mug (or other container), to which the hot java is then added. The secret interior material is designed to melt at 140F (60C), absorbing heat energy from the coffee as it does so. This reportedly allows it to cool coffee three times faster than normal.

Once the Joulie has cooled down past 140 degrees, however, it starts to solidify again, thus releasing the energy it stored while melting. This is what keeps the coffee warm for twice the time of a non-Joulified beverage.

Best results are obtained with a covered, insulated container, while heat-absorbing ceramic mugs offer the poorest performance. Users will have to experiment with different amounts of Joulies and/or with pre-heating them, depending on the size of container and whether or not they cool their coffee by adding cream.

Needless to say, the product does take up room that would otherwise be occupied by liquid – it pretty much comes down to a question of coffee quantity versus coffee temperature.

The two Daves have been making limited numbers of Coffee Joulies by hand, but are currently trying to raise funds to start automated production at an existing silverware plant. They are doing so by offering Joulies in exchange for pledges on the Kickstarter fund-raising website – US$40 will get you five, $100 will get you five and a custom Thermos travel mug, and the $500 Coffee Shop Pack will score you 20 sets of five.