A web at the bottom of a glass, or that combines American whiskey and science

In science, "random" discoveries still occur. So it was with penicillin, x-ray, viagra. And here is a fresh discovery, albeit not so significant, but interesting: it turns out that a drop of American whiskey after drying forms an amazingly beautiful pattern. What they are, why other brands of whiskey do not have such an imprint, and how scientists have found this out, Cloud4Y says.

You may have noticed that there is a difference between Scotch and American whiskey. And not only in the name (Scotch whiskey or American whiskey), but also in taste. This is due to the fact that Scotch whiskey usually acquires its taste when it is aged in old barrels, while American whiskey (bourbon) is aged in brand new burnt oak barrels. This feature was introduced in production not by accident: it helps to give a rich notes of oak in the drink, as well as speed up the aging.

However, scientists were able to find another difference between American whiskey and similar alcohol. And they found him at the bottom of the glass. Yes, yes, this is not a joke. From a dried drop of American whiskey, you can find out if it is real or not, and also determine that it is not scotch tape or Irish whiskey. However, while for this it is necessary to conduct an examination in the laboratory.


The prints are unique to each sample of proven American whiskey. Here are patterns formed by a diluted drop of whiskey from the following brands: from (a) Four Roses (22.5% ABV), (b) Heaven Hill (22.5% ABV), Maker's Mark Cask Strength (22.5% ABV), (d) Jack Daniel's Single Barrel (25% ABV), (e) Pappy Van Winkle's Family Reserve 23 Year (25% ABV), and (f)Woodford Reserve Double Oak (25% ABV)

The idea was born by chance. A young scientist named Stuart Williams once noticed that very unusual traces remain at the bottom of a glass with dried bourbon. And he began to photograph them. It seemed to him that they resemble a photo of the bottom of the eyeball. He also remembered that in 2016 the results of a similarstudyconducted for Scotch whiskeyhad already been published. In their course, it turned out that after the evaporation of the whiskey characteristic concentric circles remain (photo). In fact, there was a mechanism similar to the “coffee stain effect”"When one liquid evaporates, and solid particles that have dissolved in the liquid (for example, coffee grounds) form a ring. This is because evaporation is faster at the edge than at the center. Any remaining liquid flows outward to the edge to fill the gaps, pulling these solid particles with you.

Williams found that if he dilutes a drop of bourbon and allows it to evaporate under carefully controlled conditions, he forms what he calls the “web of whiskey”: thin strings that form various lattice patterns similar to blood vessel networks. Intrigued, he decided to conduct further research with various types of whiskey, as well as a bottle of Glenlivet Scotch whiskey for comparison. It was an ideal project for his creative vacation, and he shared the idea of ​​research with colleagues. It was assumed that the team will study the traces left after the American whiskey, and explain their appearance. It so happened that a whole group of scientists at the University of Louisville devoted themselves to a fascinating study of the prints that leave drops of American whiskey.


Study material

The Williams team tested 66 brands of American whiskey, and only one did not create a cobweb-imprint. It was corn whiskey, which matured differently, and he did not need oak barrels. The formation of a web-imprint of whiskey seems to be related to the alcohol content. Scientists emphasize that the pattern persisted only under certain conditions: at room temperature and diluting whiskey with water up to 40-50 percent.

Researchers evaporated droplets of bourbon diluted with water and studied the precipitate under a microscope. In whiskey with an alcohol concentration of at least 3%, uniform films formed. Bourbons with a volumetric alcohol level of about 10% left traces similar to coffee rings. At a concentration above 30%, a uniform film was also obtained. And only at an intermediate level, when the volumetric level of alcohol in bourbon ranged from 20% to 25%, it was possible to see unique cobweb-like structures.


The image shows that a uniform film forms after drying a drop of bourbon with a volumetric alcohol content (ABV) of more than 35%, and coffee-like patterns appear at low ABV (10%). An unexpected spider web structure occurs with ABV (20%).

Mixing in solvents (water or alcohol) reduces the effect when the drops are very small. Large droplets give more uniform spots. When tracking the movement of fluid in whiskey droplets using fluorescent markers, scientists found that surfactant molecules assemble at the edge of the droplet. This created a stress gradient that draws fluid inward (known as the Marangoni effect or “tears of wine”). There are also plant polymers that stick to glass and direct particles in a glass of whiskey. But the chemistry of whiskey is incredibly complex, so it’s still unclear exactly which ingredients are associated with these two effects.

Williams and his colleagues carefully applied tiny drops of each brand of bourbon on a glass slide and photographed prints using an inverted microscope and LED illumination. They noted significant turbulence (vortices) in the first phase of evaporation, before everything calmed down in a laminar flow, similar to the track generated by a ship. This initial turbulent phase helped determine a possible model for the formation of fingerprints. Chemicals are released during the interaction of whiskey with charred wood barrels. They form lumps (micelles), and evaporating turbulence causes them to collapse into the final residual sample: a web-like imprint.


That is, solid microparticles of carbonized wood fall into whiskey. And after evaporation, the liquids remain on the surface of the glass. The web of whiskey was formed in different varieties of American whiskey, but not in distillates, which indicates that the charred new oak barrel and the ripening conditions play an important role.


This is a photograph taken by an electron microscope. You see a single cobweblike structure resembling a coiled monolayer (covered with a thin layer of gold to improve image performance).

How useful is this study? Well, firstly, it just shows us the beauty of whiskey (a site with other photos ). You can admire these prints for a long time, they have something cosmic and mysterious.



Secondly, this discovery may be useful to producers and consumers. The former will be able to receive additional information about the maturation of the product, and the latter will protect themselves from low-quality alcohol. After all, if after drying the diluted American whiskey a web is not formed, but a film, this may mean that the whiskey was made using a different technology. In other words, this is not bourbon, but a fake.

What else can be useful to read on the Cloud4Y blog

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