Show me what you’re made of

With all this talk of cocktail shaker shape, size and (crucially) technique, are any of us thinking about what our cocktail shakers are made of?
Recent trials have shown that the way in which we shake has little effect on the dilution or temperature of a shaken cocktail. The act of aggressively mixing spirits and liquors with ice causes the ice to melt and the drink to chill, no matter how you choose to do it. That’s not to say that certain shaking styles don’t affect the aeration or texture of a finished drink, but that’s a discussion for another time.
What is interesting is that the melting of the ice is directly proportional to the chilling of the drink. In other words—you can’t have chilling without dilution.
Before it’s shaken, a Talisker Sour has lots of heat energy stored in it from all the room temperature ingredients. Ice requires quite a lot of energy to melt (the temperature of the ice makes very little difference at all) and nearly all of that energy comes from the liquid components of the cocktail. As the ice "steals" energy from the Whisky, lemon and sugar, the ingredients chill down, getting colder and colder the more the ice melts. Eventually the contents of the shaker reach a kind of plateau (this usually happens at about 23°F) where there is insufficient energy left in the drink to continue melting the ice. The temperature/dilution will remain fairly stable even after minutes of shaking.
The material your shaker is made from does have a slight effect on this, since some materials are more thermally conductive than others. Copper and silver, for example, absorb energy very easily. This means that a copper shaker will happily "steal" lots of energy from your ice cubes. Not good, since the extra dilution of the cocktail means that the drinks volume increases, which in turn means even more chilling power (and dilution) is required to hit the right temperature.
So what’s the best material? Well, steel is by far the most cost effective metal. It’s cheap and has a reasonably low conductivity. Surprisingly, glass is one of the best materials, but for those of you who want to hold something shiny, titanium is very good indeed (but expensive). The best of all though? Polystyrene. A Styrofoam shaker would be the ultimate shaker, since it’s an insulator, ensuring that all chilling power of the ice is well contained inside the shaker.
Make your ice melt for your drink not your shaker!
Tristan Stephenson is the co-owner of three of London's top cocktail bars, as well as a keen cocktail historian, pioneer of modernist bartending techniques and amateur flavor scientist.