What Are Tears Of Wine?

Church windows, curtains, tears or legs . . . They have many different names, but these liquid layers on the inner wall of a wine glass have one thing in common: Providing information about the concentration of various ingredients (such as alcohol content, sugar and additive percentages) in the wine.

When wine cries

Flowing streaks can form inside a glass of wine when it's swirled. The liquid briefly rises as if by magic, then slowly runs down the glass and forms into so-called teardrops.

Marangoni Effect

This is called the Marangoni effect, named after the Italian physicist Carlo Marangoni. The physicist studied the surface tension of liquids and their effect on one another. Wine consists of various components such as alcohol and water. If you wet the glass with wine above the mirror, the alcohol evaporates faster than water at this point, which leads to an increase in surface tension. Since the liquid film is thinnest at the upper edge, the effect is strongest here, as better ventilation is possible. As a result, the top film (the remaining water), which has a higher surface tension, so to speak, pulls the lower layers with the wine mixture upwards. For a certain time, this effect is self -sustaining, since the alcohol that is drawn upwards evaporates again immediately.
Over time, a little more residual liquid, which consists of components such as sugar that do not evaporate, collects at the top edge. This accumulation becomes heavier and heavier, runs back down into the glass and creates the typical wine tears.

It was previously believed that glycerol, which is formed during alcoholic fermentation by yeasts, is responsible for this phenomenon as it affects the viscosity of the wine. Although glycerin is essentially an alcohol, it has a surface tension similar to that of water and evaporates relatively slowly. It therefore has no impact on the Marangoni effect.

What the church windows say about the wine

As a rule of thumb, remember: The smaller the distances between the tears and the more pointed the shape is (a church window in the style of a pointed arch), the more alcohol and more additives the wine has. The sugar content enhances this effect.
On the other hand, thicker and rounder tears (or an arched church window) as well as a wide distance between the streaks can be an indication of a lower alcohol content and a lower concentration of various ingredients. If hardly any streaks can be seen, then it is a light wine with little alcohol content.

Conclusion

This method is only a rough guide and is slightly controversial, partly because the shape of the wine glass can also affect the appearance of the tears. This method also only provides information about the alcohol and sugar content, and is not an indicator of the quality of the wine.

Photo credits: @marcelgross.ch via Unsplash