The shaker is part of the basic equipment of every good mixologist and, thanks to several popular films of the 90s, shaking is, in common imagination, one of the sexiest gestures.
But when is it actually necessary to shake a cocktail and when is it not?
First, you should know that when preparing a cocktail, a shaker is needed when using ingredients with different densities, like juices and syrups as these need to be ‘aerated’ to give them the right consistency. Using good quality ice is also very important, so that the cocktail is not too diluted, or tastes strange: for example, it may not be a good idea to keep ice in the freezer next to chopped parsley, unless parsley is an ingredient of your drink!
Instead, the shaker is replaced by the mixing glass when using ingredients of the same density, usually alcoholic (e.g. Vermouth and gin, two of the basic ingredients of Negroni). The mixing glass is perfect for diluting, thus lowering the alcohol content of the cocktail, as well as for mixing and chilling. The bar spoon (or stirrer) often goes hand in hand with the mixing glass. This is a very long-handled spoon needed to stir ingredients when using very tall glasses or jugs.
If we take a close look at the art of mixology, we will notice that many cocktails are also prepared directly in the glass. This is the case of those preparations with ingredients that do not have different densities and it is important to end the drink with a gas component (like for the Americano, in Spritz and in Gin Tonic), which obviously cannot be shaken.