2019 Study Finds Tapping 1,031 Beer Cans Does Not Prevent Liquid Loss

Q: Why does a massive scientific study suggest your lifelong habit of tapping a soda can might actually be making the fizzing worse?

Yes — the evidence suggests tapping is mostly a myth and can sometimes backfire. The physics inside a shaken can explains why. Carbonated drinks hold dissolved carbon dioxide under pressure. Shaking creates tiny bubbles at scratches, dust, and rough spots known as nucleation sites. When you open the can, pressure drops suddenly, those bubbles expand fast, and foam rushes out. Tapping may help only in a narrow way: a very gentle tap can dislodge some bubbles stuck to the can wall and let them rise into the air pocket at the top. But that effect is small and unreliable. The same mechanical action can also generate new pressure disturbances, create more low-pressure zones, and produce additional bubbles. In other words, if you tap too hard or too much, you may be adding to the problem rather than solving it. That is why a large 2019 preprint study of 1,031 beer cans matters. Researchers compared shaken and unshaken cans, tapped and untapped, and found no statistically significant difference in how much beer was lost. Beer is not identical to soda, but experts say the study is still strong evidence that tapping is not a dependable fix for carbonated drinks. The better remedy is to let the can sit upright for several minutes, keep it cold, and if necessary open it slowly so gas escapes gradually. Those methods address the real cause: unstable CO₂ bubbles and sudden pressure release.

2 articles · Updated · Livescience.com · Aug 22

A 2019 preprint tested 1,031 beer cans and found no statistically significant difference in spillover between tapped and untapped cans, whether the cans had been shaken or not.
Researchers split cans into four groups—shaken and tapped, shaken and untapped, unshaken and tapped, and unshaken and untapped—after flicking tapped cans three times before opening.
The physics helps explain why: shaking creates pressure waves and suspended CO2 bubbles, while tapping may dislodge some bubbles but can also generate more, canceling out any benefit.
Experts said the more reliable fix is time and temperature—let a shaken can sit upright for several minutes, keep it cold, or open it slowly to vent gas through a small slit.