Mathematicians have come up with a formula that predicts how the head on a pint of beer will change after pouring.
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Asked why some beers such as Guinness have a creamy head that persists longer than those of many lagers, Professor Srolovitz explained:
"What this theory does is tell you how every single bubble in the froth will evolve. There are some materials properties that go into the final equation.
"So for beer, it will be the diffusivity of the gas in that little liquid layer that's in the wall of the bubble. Another is the surface tension.
He added: "I don't know the tricks that Guinness uses; they could be adding a little surfactant to get the head just right. That is just pure speculation on my part."
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Asked why some beers such as Guinness have a creamy head that persists longer than those of many lagers, Professor Srolovitz explained:
"What this theory does is tell you how every single bubble in the froth will evolve. There are some materials properties that go into the final equation.
"So for beer, it will be the diffusivity of the gas in that little liquid layer that's in the wall of the bubble. Another is the surface tension.
He added: "I don't know the tricks that Guinness uses; they could be adding a little surfactant to get the head just right. That is just pure speculation on my part."

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