For decades, a phenomenon called the “coffee ring effect” has fascinated scientists. The coffee ring effect describes how spilled coffee forms a ring as the coffee evaporates, leaving solid particles around the edge of the spill. But now a new fascination has arisen with American whiskey.
When liquids like coffee and whiskey evaporate, they leave tiny solid particles in a pattern. This pattern depends on the type of liquid. A group of researchers from the Department of Mechanical Engineering at the University of Louisville discovered that when drops of whiskey dry up, these solids form a web-like pattern. The results are published in ACS Nano; the researchers believe that these “whiskey webs” could one day help to identify counterfeit whiskey.
The researchers discovered that whiskey webs aren’t found in Canadian whiskey or Scotch, but they are present in diluted American whiskey. There was some suggestion that the webs even differed by the brand of whiskey. For this study, the researchers wanted to find out if they could use these distinctive web patterns like fingerprints.
The scientists studied drops of diluted American whiskey as the liquid evaporated. As the whiskey evaporated, certain compounds clustered together forming a monolayer (a layer that is one molecule or cell in thickness). As the drop continued to dry, these monolayers collapsed, which is what created the web-like pattern. 90% of the time, the researchers were able to identify the brand of American whiskey by examining the web pattern.