Guinness has a plastic ball in the can—called a widget —to recreate the creamy, draught‑style pour and thick foam you’d normally get from Guinness on tap.

What the ball actually does

Inside that little hollow plastic ball is nitrogen and a bit of beer trapped under pressure. When the can is sealed at the brewery, liquid nitrogen is added so pressure builds and forces some beer and gas into the widget through a tiny hole.

The magic happens when you open the can:

  • The pressure in the can suddenly drops.
  • The pressure inside the widget is still higher, so nitrogen and beer jet back out through the tiny hole into the rest of the can.
  • This blast creates millions of tiny nitrogen bubbles, giving Guinness its signature creamy head and velvety texture instead of big fizzy bubbles.

That’s why a properly poured Guinness from a can looks and feels closer to a pub draught than a typical canned beer.

Why nitrogen and not “normal” carbonation?

Most beers use carbon dioxide, which makes larger, sharper bubbles and a more biting fizz. Guinness relies heavily on nitrogen, which:

  • Produces much smaller bubbles for a smoother, silkier mouthfeel.
  • Creates that thick, slow‑cascading foam on top of the stout.

Nitrogen doesn’t stay dissolved in beer as easily in a closed can, which is why the widget was invented—to release nitrogen at the exact moment you open it, instead of trying to keep it stable the whole time.

A quick bit of history

  • Guinness patented the widget concept around 1969, and first released a widget can in 1989.
  • The original design was a disc at the bottom of the can, later replaced (in 1997) with the floating, ping‑pong‑ball‑style “smoothifier” used today.
  • The idea was so successful that other nitro beers like Murphy’s Stout and Boddingtons Pub Ale also use widgets in their cans.

How to pour it “properly” at home

To get the full effect from that widget:

  1. Chill the can well in the fridge. Guinness is designed to be served cold.
  1. Open the can smoothly (you’ll hear the characteristic “psshhh” as the widget fires).
  1. Pour into a glass in one steady motion, tilting the glass around 45 degrees, then straightening as it fills to build the creamy head.

That’s how the little ball turns a simple can into something very close to a pub pour. Meta description:
Wondering why does Guinness have a ball in the can? Learn how the nitrogen widget works, why it matters for taste and foam, and the story behind this clever invention. Information gathered from public forums or data available on the internet and portrayed here.