The very thought of legs in the context of wine conjures up the image of swirling glasses in a sea of tuxedo clad men. Oohs and Ahs fill the air as everyone examines the wine legs, those droplets on the glass that the French so poetically dub “wine tears".
Using terms such as “body", “glycerin", “circles around the august body” everyone agrees that ,based on the prophecy of the wine legs alone, this is indeed a fine wine.
The scene is a compelling one, indicative of upper class and privilege. While even the most ardent anti- wine snob tries to conceal it, there is more often than not a shimmer of exclusivity while engaging in the passion of wine tasting.
It is for this reason more than any other that the myth of “wine legs” as an indicator of wine quality continues to exist. It is further aggravated by the greater myth that the legs are linked to the amount of glycerin in the wine. It is not uncommon for those who teach about wine to propagate this myth. Many believe it is true, but a few offend the wine world as they know better but are simply too lazy to correct the misconception.
Legs are the result of the simple fact that the alcohol (ethanol) in wine evaporates faster than water. This is called the Marangoni effect. The alcohol crawls up the glass as it evaporates, but the film of water remains on top and pushes up the alcohol in an arch. Eventually gravity wins and the water’ surface tension is broken, and the droplets run down in tears.
The greater the alcohol content, the greater the leg. While this would seem to be a handy indicator in a blind tasting, in fact the percentage of alcohol needed to notice a difference is so great that it would be the difference between a table wine and a fortified wine. It is unlikely that legs would be necessary to help you tell these two types of wines apart.
As to the glycerin, first and foremost there is no glycerin in wine. Glycerin is a syrup that one buys at the drug store. Glycerol is the correct term and it is alcohol. The amount of alcohol in wine is very small, and while it contributes to sweetness, it does not contribute to the body.
Whereas the imagery and poetry of the wine tears is overwhelming, it is in fact no true test of body nor is it due to glycerin or glycerol. While legs are an indicator of the alcohol level, it is a redundant observation and in no way useful in evaluating true wine quality.
A votre bonne sante!