The ball in a Guinness can is a small plastic “widget” that releases nitrogen when you open the can, creating the creamy head and smooth texture you normally get from Guinness on tap.

What the ball actually is

  • The ball is a hollow plastic sphere with a tiny hole, called a widget.
  • It sits in the beer during canning and is preloaded with pressurized nitrogen and a little beer.

How the widget works

  • When the can is sealed, the beer and widget are pressurized with nitrogen, some of which dissolves into the beer.
  • When you open the can, the pressure suddenly drops, and the nitrogen-rich beer inside the widget jets out through the tiny hole, creating a surge of tiny bubbles.

Why Guinness uses it

  • That nitrogen surge produces the signature thick, creamy head and smooth mouthfeel associated with draught Guinness in pubs.
  • The widget was developed so canned Guinness could taste and pour more like a freshly pulled pint from the bar, not a typical fizzy canned beer.

Fun extras and forum chatter

  • Beer fans often discover the widget only after cutting open or finishing a can, leading to recurring “what’s this ball?” threads on forums and Reddit.
  • The Guinness widget has even been highlighted as a notable packaging invention, praised for using simple physics to upgrade the drinking experience.

TL;DR: The “ball” in a Guinness can is a nitrogen widget that, when the can is opened, releases nitrogen-rich beer to create the smooth, creamy head of a draught pint.

Information gathered from public forums or data available on the internet and portrayed here.