I was just making a stout float and noticed that my beer foamed up a ton.

It's not a very carbonated beer (there was barely a hiss when I opened the growler), yet the head was several inches with not very much beer poured into the chilled mug.

What causes this massive head and is there a good way to prevent it?

  • 4
    Why are you pouring beer over ice cream? Commented Feb 7, 2014 at 7:14
  • 7
    @LucasKauffman Because it's delicious.
    – wax eagle
    Commented Feb 7, 2014 at 11:00
  • 1
    Ha, I will have to try this. A chocolate stout or a milk-stout would probably work great.
    – darwhen
    Commented Feb 11, 2014 at 4:33
  • Contrary to what you might expect, the flavours of beer and chocolate go together quite well. You might not pour beer on your ice cream every day but if you've ever been eating a bowl of chocolate ice cream and given a beer to drink you will discover this. By the way if you like beer, especially bitter ones, but think you are not a fan of chocolate, try some pure dark unsweetened chocolate (often labelled "bitter"), you might be surprised what chocolate really tastes like. Commented Mar 30, 2014 at 4:17

1 Answer 1


For the same reason that root beer floats behave in a similar fashion. Even though there is less carbonation than in root beer (and I presume similarly less foam, though still a significant quantity) the irregular surface of the ice cream offers a massively larger number of nucleation sites than the smooth glass of your favorite beer vessel. These nucleation sites cause the CO2 to come out of solution, and voila, much foam does appear. I believe that the ice cream has properties that enhance the foaming effect as well.

  • I don't know if nucleation sites is a real thing but this answer sounds legit! And now I have something else to learn about. Commented Feb 10, 2014 at 20:04
  • Bill I assure you that nucleation sites are a real, and are in fact a common consideration in chemical matters. :) Great answer!
    – darwhen
    Commented Feb 11, 2014 at 4:30

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