How do you call it in English when the foam loses its volume?

Question

In my language (Russian) there are at least 3 words that can be used for the process of foam losing its volume (for example, in a beer mug) and going away. But none of the dictionaries I use give any kind of translation corresponding to those meanings of these words (regarding beer foam going away with time).

One of the problems is, as I see in the articles about beer foam, that the English internet suggests to either serve the beer without the foam at all or with little foam, and gives advice for that, or to remove it after serving if you fail. But what you would typically see in a Russian bar is a bartender pouring some beer in your mug, waitng a bit for the foam to lose some volume, then pour in more beer until the needed volume of the liquid is served, so I can't even find the word in the English articles about serving beer.

Anyway: how do I call the process of foam losing its volume, or waiting for it to lose the volume?

Answer 1

As has been noted, a specific term does not appear to exist in English. The foam on a beer is called the head. I think the simplest way to describe this is to use go down, for example:

I'm going to wait for the head to go down before I finish pouring.

If I were writing formally I would use "recede", as is used on the wikipedia page on beer head

English ales, and particularly Irish stouts, tend to form a small but dense and long-lasting head. The beer glass is three-quarter filled, then allowed to settle, then finally topped off. They will do that by pouring more beer into the glass, causing the bubbles to overflow. But if you are served a beer that has too much foam on top you can ask the barperson:

Can you take the head off that for me?

Lagers are often served with no head at all by holding the glass at an angle while pouring.

Anyone interested in beer foam should read A Leike's seminal paper: Demonstration of the exponential decay law using beer froth

Answer 2

We say say "the head went flat".

If the Catholic Church lost control over the printed word with the invention of the printing press — the technological weapon that ensured Luther's success — it lost control over beer with the rise of hops. "The head went flat on monastic beer," says Bostwick. "Did Protestantism explicitly promote hops? I don't think so. But did it encourage the use of hops? I would say, yes, probably." [emphasis added]

When you have a mug under the tap and the beer foams up in the glass, you can wait for the foam to settle before pouring more.

Some beers foam far less than others, and sometimes the foam is artificial from nitrogen delivery systems or from CO₂ added to it.

Answer 3

You could say something like

The foam deflates.
I am waiting for the foam to deflate.

Answer 4

Disappear, dissipate, evanesce, shrink, subside could each be used in the proper context. I personally would use "flatten" only with respect to foam on drinks. Again personally, I would probably use "shrink" or "subside" if foam was still present and "disappear" if the foam was entirely gone. I am going to see how "evanesce" goes over at the local bar though.