In a reflective moment with a glass of beer (the thick, creamy kind that comes in a can with a ‘widget’ at the bottom and is somewhere between ale and stout) I was interested to note how long the bubbles took to settle into the head (of the beer, not mine). This seemed counter-intuitive to me. Surely gas bubbles released when the can is opened and the beer poured into a glass should float quickly to the top of the liquid (like in lager or other fizzy drinks) rather than swirl around and generally sort of hang about taking their time…
Is it to do with the small size of the bubbles, the density or viscosity of the beer or what? What’s happening in my beer glass?