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Freshman year, my first semester, I was taught many things. One important trick I learned was when I was passed a beer in a 12 oz. plastic cup, I could eliminate the fresh foamy head by wiping my nose and touching it to the top of the foam.

I thought to do this recently with soda (as it seems soda head is more persistent). The trick works there too.

What is the chemistry behind this? Is it the salinity? Could I use something less revolting than nose grease to do the same trick?

Jason P Sallinger
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    Reduced surface tension. Many craft beer drinkers want exactly the opposite effect: they try to keep their classes so-called "beer clean" in order to retain the head. Soap and greasy residue are two big foam-killers. – SendersReagent Apr 26 '19 at 14:30
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    The proper beer glass should be wet before filling. As indirect consequence, it helps keeping the foam of the Czech beer.. – Poutnik Apr 26 '19 at 16:12
  • @Poutnik True, filling a dry glass foams like hell and thus takes forever. By the time it lands on your table, it's stale. – Karl Apr 26 '19 at 20:31
  • Inspired by your family name: in Austria serious barmen might take up to five minutes or so for crafting an impressively thick and persistent head (called Krone, crown). Prost! – Alchimista Apr 27 '19 at 06:13

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Any oil should work.

Naturally occurring surfactants, such as lecithin, make bubbles or foam because one end of the detergent molecule is hydrophilic while the opposing end is hydrophobic (not rabietic, though). Without oil, the hydrophobic end prefers air to water, encapsulating the air. With oil added, though, the water-repellent end is attracted to the oil, forming micelles, instead.

You could put vegetable oil or mineral oil on your finger, but then the server might wonder why you stick your finger in the beer.

You might also try making a beer-powered boat! Tell your server, and ask for a free beer to prove that this works.

DrMoishe Pippik
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  • And pop goes your foam (Schaumkrone (Crown) or Blume (flower) in German. God are we a poetic people.). I can see the freshman humour in trying this on someone else's beer, but your own? :-| – Karl Apr 26 '19 at 20:35
  • BTW, my uncle, when he was 8 years old or so, would get beer in a stein for his father at the pub downstairs (in ~1915, nobody cared). He'd talk to the bartender for a while, the bloom (well, head) would be off the beer, and he would say "My father will not be happy with me bringing him less than a full stein." The bartender wasn't fooled, but he always refilled to the top for the kid. – DrMoishe Pippik Apr 26 '19 at 21:13