Wine: Great Legs and a Firm Ass

Tim Nodland, Winemaker

Author: Tim Nodland

Almost every time I attend a wine tasting I hear some know-it-all say that a wine is well made because it has “great legs”. When someone refers to “great legs” they are referring to the droplets of liquid coming down the side of the wine glass like tears.  Pick up your glass, perhaps you have in it the Nodland Cellars Private Blend, swirl it and let the wine hit the side of the glass. You will see liquid coming down the side of the glass like tears. In wine jargon these are the “legs”. The French call them “tears”. Contrary to what you will hear at wine tastings, these “legs” or “tears” do not indicate the quality of the wine.

The “tears” are present on the side of the wine glass because alcohol evaporates faster than water. The alcohol crawls up the glass as it evaporates but the film of water on top pushes it into an arch until gravity wins over and the water’s surface tension is broken and the water runs back down the side of the glass in tears.

Stated another way, the “legs” effect is a result of alcohol having a lower surface tension than water. When water and alcohol are mixed together on the side of the wine glass, the region of the glass with the lower concentration of alcohol has a greater surface tension and will pull on the surrounding fluid more than the area with the higher alcohol concentration and the lower surface tension. The water flows away from the areas with a higher alcohol concentration and down the side of the glass.

To prove this principle of basic physics you can cover the glass to stop the evaporation and the “legs” will not form.

And so it is a myth that the legs on the side of a glass indicate the quality of the wine and is just a matter of fluid dynamics. It is also wrong that the legs indicate the presence of glycerol in the wine or from it you can tell how much alcohol is in the wine. It would take too large amount of glycerol or too great of increase in alcohol to notice a change in the effect.

So at the next wine tasting, beg to disagree about the meaning of “legs” on the side of a wine glass. Tell your friends that it is merely the “Gibbs-Marangoni effect” understood and explained by scientists in 1855. Or if you wish to amuse yourself at their expense, tell them that the wine not only has great legs but also a very firm ass.

 

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