Specific Gravities Of Spirits - The Key To Layering

Liquids have a specific gravity (or weight) in comparison to water. The specific gravity is a number compared to water (which is assigned the specific gravity number of 1). Those liquids that are heavier than water have a number higher than 1, those that are lighter than water have a number lower than 1. A liquid that is lighter than water will float on top, those that are heavier will sink below. This is how layering is achieved in drink recipes.

Alcohol is lighter than water, the higher than content of alcohol the lower the weight of the liquid in relationship to water. Therefore when pouring liquids in a drink to create a layered effect the heaviest should be poured first with the lightest last. For example, a B-52 shooter has the ingredients Baileys Irish Cream, Grand Marnier & Kahlua. Of these three Kahlua (1.15) is the heaviest and is poured first, Baileys (1.07) is the next heaviest and goes next, Grand Marnier (1.03) is the lightest (most alcohol per volume) and is the last ingredient. When properly poured there will be three distinct layers.

There are two charts below, one listing the alcohol ingredients by name and the other by specific gravity with the heaviest first (Grenadine with a specific gravity of 1.18  is 18 percent heavier than water and is at the top). Use this chart to determine the order of the specific ingredients working from the top down. Keep in mind that ingredients that have specific gravities that are very close are hard to layer, the bigger the difference the easier it is to keep layers cleanly separated. Pour the ingredients slowly down the side of the glass or use the back of a spoon to reduce the force of the liquid and prevent it from breaking into the previous layer. If you are using a very narrow glass, pour the liquids over a cherry rather than a spoon. Using liquor pourers with thin pouring spouts is recommended as the easiest manner to pour the liquids. When referring to these charts keep in mind that specific gravities can vary depending on a number of factors such as brand name and age, some experimentation may be required to obtain the desired result.

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