tapping your can of beer

[93Regina]

Does tapping your can of beer really keep it from fizzing all over
you?

A team of researchers at the University of Denmark has tested the
popular notion that tapping a can of beer after it has been shaken
will prevent it from spraying when it is opened. Their paper describes
a trial they carried out along with their conclusions, and is
available on the arXiv preprint server.

Anyone who drinks beer on a regular basis knows about tapping the beer
container a few times to get it to settle down before opening it. Some
drinkers tap the lid or the top, and some tap the side of the bottle
or can. Whichever approach is used, the goal is always the same—to
prevent beer from spewing out when the can or bottle is opened. Beer
and soda drinkers also know that shaking bottles or cans before
opening is a big non-no—doing so will result in beer spewing out like
champagne. In many circles, it is believed that some tapping can
reduce or prevent such spewing—but as the researchers with this new
effort note, the idea has never been tested scientifically.

To find out if tapping works, the researchers enlisted the assistance
of a beer company and were rewarded with over 1000 donated cans of
beer. Next, they enlisted student volunteers as testers. First, all of
the cans were weighed to measure the contents. Then half of the cans
of beer were put on a mechanical shaker for two minutes; the other
half were left as they were delivered. Then half of the volunteers in
both groups were asked to tap a can on its side three times before
opening it. All of the cans were weighed again to see how much beer
was lost after the can was opened.

The researchers report that they saw no benefit to tapping the can
before opening—tapped cans, whether shaken beforehand or not, lost
just as much beer after opening as un-tapped cans. The researchers
also report that the beer was not wasted—it was given away to anyone
on campus who cared to drink it.

https://phys.org/news/2019-12-beer-fizzing.html