Layer

Layering is the technique of stacking multiple liquids in a glass so each remains in a distinct visible band, creating drinks with dramatic color striping. It is the more precise, multi-layer extension of the float technique. Layering exploits differences in specific gravity: denser liquids stay at the bottom while less dense liquids float above. The primary factor in cocktail specific gravity is sugar content. High-sugar liqueurs like coffee liqueurs and cream liqueurs are denser and go on the bottom; dry high-proof spirits and orange liqueurs are lighter and go on top. The classic demonstration of layering is the B-52: Kahlúa forms the base (very high sugar, densest layer), Baileys Irish Cream sits in the middle (moderate sugar and fat from cream), and Grand Marnier rests on top (drier, lighter orange liqueur). The Pousse Café, a nineteenth-century French cocktail construction built from five to seven different colored liqueurs layered by density, represents the most technically demanding version of this concept. The Tequila Sunrise uses a closely related principle where grenadine, heavier than the tequila and orange juice above it, is poured in after assembly and sinks to create the gradient at the base. Execution requires patience and a steady hand. The technique for each new layer is to hold a bar spoon with its curved back facing up, touching the inside wall of the glass just above the previous layer, and pour the new ingredient very slowly over the convex surface. The spoon disperses the incoming liquid laterally rather than letting it fall directly into the layer below. Temperature affects results: chilled ingredients are very slightly denser than room-temperature versions. Good layering also depends on the glass — straight-sided shot glasses and clear tulip glasses reveal layers most clearly.