Why do you spray a glass with water before pouring beer?

Spraying a glass with water before pouring beer serves a couple of important purposes, primarily related to ensuring the best sensory and aesthetic experience when serving beer. When a glass has residual sanitizer from cleaning, it can negatively affect the beer's aroma and flavor. Additionally, proper glass preparation promotes optimal head formation, which is crucial for enhancing the beer's aroma. The presence of water helps to create a more conducive environment for bubbles to form and stabilize, leading to a better head on the beer when it is poured.

In contrast, diluting the beer, increasing carbonation, or cooling the beer are not the primary reasons for this practice. Pouring beer into a glass that has been sprayed with water does not aim to dilute the beer, as this would reduce its overall flavor intensity. Additionally, while some may assume that water could affect carbonation levels, the right amount of water can actually help maintain the carbonation of the beer by encouraging proper head retention instead. Lastly, cooling the beer is not a primary function of spraying water on the glass; the temperature of the beer itself is what most directly affects its enjoyment and should be properly managed before pouring.