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The Fascinating Science Behind Beer Foam

timothy posted about 6 months ago | from the ok-now-explain-my-flickering-lights dept.

Beer 73

RenderSeven writes "Science has so far been at a loss to explain why tapping a beer bottle with another causes it to explosively foam over. Thanks to a grant from the Spanish Ministry of Economy and Competitiveness, a research team at the University of Madrid studying fluid mechanics has found the answer with some fascinating slow-motion video. Their soon-to-be-published paper found that tapping the bottle (or shooting it with a laser) causes a series of compression and expansion waves, that generate unstable buoyant plumes, quickly turning most of the liquid into foam. PhysicsBuzz notes that the process is very rapid and nearly unstoppable once started."

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LOL .... (2)

gstoddart (321705) | about 6 months ago | (#45225639)

Their soon-to-be-published paper found that tapping the bottle (or shooting it with a laser)

I don't know about mixing beer and lasers.

Just saying. ;-)

Still, maybe we can look forward to beer bottles which are designed to prevent catastrophic foaming in cases like this.

Re:LOL .... (0)

mcgrew (92797) | about 6 months ago | (#45227773)

I don't know about mixing beer and lasers.

I think you have a point there; the statement "Science has so far been at a loss to explain why tapping a beer bottle with another causes it to explosively foam over" really seems suspicious to me, because the answer seems too obvious. More likely, these guys needed a paper, were drinking while trying to figure out what to write a paper on and one of them says "I wonder why that beer foams over." Next day, easy paper because they're sober and it's obvious that tapping the bottle causes a series of compression and expansion waves that generate unstable buoyant plumes, quickly turning most of the liquid into foam. Christ, I could figure that out and I'm no physicist, I just read a lot. Hmmm... that does sound reminiscent of something the professor of an undergrad general studies physics class I took over 30 years ago said. Maybe, it was a long time ago.

Easy money, these guys are pretty smart. "Hey, we can test our (pretty damned obvious) hypothesis with a laser. I'll bet it makes he beer explode!"

Let's see, I think I'll replicate their experiment... now where did I leave the cat's laser?

Beer and lasers. (4, Funny)

fahrbot-bot (874524) | about 6 months ago | (#45225677)

Their soon-to-be-published paper found that tapping the bottle (or shooting it with a laser) causes a series of compression and expansion waves, that generate unstable buoyant plumes, quickly turning most of the liquid into foam.

Just one more reason sharks are lousy drinking buddies.

Actually there is a ninja defense trick here (2)

GoodNewsJimDotCom (2244874) | about 6 months ago | (#45225707)

It says once the bottle is tapped, you have 1 ms to put your thumb over the mouth of the beer bottle. Of course even gamers know its hard to react sub 33ms, so 1 ms looks bleak... But look at it from another angle: If you see some jerk coming to tap your bottle, there is some reaction time there! So thumbs over the opening folks.

Re:Actually there is a ninja defense trick here (1)

TheCarp (96830) | about 6 months ago | (#45226661)

Let me guess, you are, in fact, one of "those jerks" and you realized that now you may have a way to convince people to let you smack their thumb instead?

Sorry, I remember the "hit my hand" joke.

There really is a trick (1)

demon driver (1046738) | about 6 months ago | (#45228427)

There is a working trick, and it works because the real eruption needs slightly longer than one microsecond (remember, TFA said it's one microsecond until the first bubble implodes, and one bubble doesn't make an eruption yet): as fast as you can, grab the bottle, put it to your mouth, and drink! Many years ago, there was a time I was quite good at it... It doesn't even need much training, only a minimum of alertness and quick response. Which, of course, deteriorates with the amount of beer you've already drunk...

Re:Actually there is a ninja defense trick here (1)

S.O.B. (136083) | about 6 months ago | (#45234691)

And if you're not a ninja I have two better solutions:

1) Drink from a glass.
2) Drink from cans.

I make beer... (4, Informative)

dargaud (518470) | about 6 months ago | (#45225721)

...and foam is a mix of two things: a gas (here CO2) and a liquid that can hold the gas, meaning something a lot more complex than water. Usually it's a mix of proteins, in a way similar to the way gluten holds the bubbles inside the bread to let it rise. I have some bottles that, if opened brutally, will turn entirely to foam. Others will have the wanted 'normal' foam: a few inches which lasts for a long time. Others have lots of gas but no foam. Soda makers in recent years have actually started adding anti foaming additives to their drinks; have you noticed that you can't shake a friend's coke and have it explode in his face anymore ?

Re:I make beer... (5, Funny)

jm007 (746228) | about 6 months ago | (#45225833)

Ah... that explains it. I had become somewhat nervous about the beverages handed to me by my grade school son ever since he learned about that prank. Nothing ever happened... and I thought he was just being a good, thoughtful boy.

Re:I make beer... (4, Informative)

gstoddart (321705) | about 6 months ago | (#45225889)

Ah... that explains it. I had become somewhat nervous about the beverages handed to me by my grade school son ever since he learned about that prank. Nothing ever happened

I learned a long time ago how to open a can without too much fear of this.

Tap the top of the can a couple of times, and crack it open just enough to let a small amount of pressure escape, and wait a little while. It might foam a little, but you can actually 'burp' off most of the pressure if you're careful.

Even back in the 80s I could open a can which had been shaken without much incidence of spraying. And I've always opened cans that way since because, well, my friends weren't good, thoughtful kids when it came to that. ;-)

Re:I make beer... (1)

SiChemist (575005) | about 6 months ago | (#45226159)

You have to tap the sides. Tapping the top doesn't help much.

Link [youtube.com]

Re:I make beer... (1)

gstoddart (321705) | about 6 months ago | (#45226271)

You have to tap the sides. Tapping the top doesn't help much.

And yet, I have successfully used my technique for 3 decades.

From which we can conclude: either 1) I've never actually been given a can which was shaken, 2) my technique also works, 3) or cans don't foam up and it's a myth.

To the best of my knowledge, 1) and 3) are provably false.

Re:I make beer... (1)

AvitarX (172628) | about 6 months ago | (#45226387)

4) the main useful thing you did was the slow opening maybe.

Re:I make beer... (2)

gstoddart (321705) | about 6 months ago | (#45226461)

4) the main useful thing you did was the slow opening maybe.

Entirely possible. I haven't done rigorous testing to isolate which aspects of it are the biggest factor. If someone was to give me a grant I might. ;-)

But I successfully went through my adolescence opening cans that I knew my friends had shaken and never got sprayed in the face.

So I pretty much have kept opening cans that way since.

Re:I make beer... (1)

TheCarp (96830) | about 6 months ago | (#45226771)

> Entirely possible. I haven't done rigorous testing to isolate which aspects of it are the biggest factor.

Let me give you my results then. I have had the same sort of success with the same sort of situation. However, I have never bothered to 'tap the can' first, it never even occured to me to do so.

There is actually some headspace in the can anyway, just holding it rightside up puts the bubble at the top. If you need evidence of this, try a "Kamakazi":

Step 1: Tip can over to aprox 45 degrees so the "top" is actually a point on the bottom rim of the can.
Step 2: Use a knife to puncture the can near the ridge
Step 3: Turn the can over and place your lips over the small hole
Step 4: Open the top tab

If done properly, you will be chugging a beer about as fast as you can from a can. Repeat until you miss air space in step 2. I saw someone do this once at a LAN party (get off my lawn) and they managed to put a trail of beer straight across my laptop keyboard and screen.... from the next room.

Re:I make beer... (0)

Anonymous Coward | about 6 months ago | (#45227317)

The slow opening is indeed the secret here though you want to wait a LONG time if you're dealing with root beer since the head is one of the main attractions. I've actually researched and demonstrated this concept over the past 2 decades.

Re:I make beer... (1)

ottothecow (600101) | about 6 months ago | (#45233917)

I remember reading somewhere that the secret is time. All of those tricks like tapping the top/side, opening slowly, etc., cause you to wait a little bit longer before opening the can.

None of the tricks actually do anything, but the explosive force actually dissipates pretty fast (and when you do open a shaken can and get spray, you are getting the tail end of the force that built up). Pausing to set the can down still and tap on it gives it enough time to dissipate below the point of spraying all over the place.

Re:I make beer... (1)

SiChemist (575005) | about 6 months ago | (#45271225)

If you follow the link, you can see how tapping the sides works. It's not waiting that prevents the overflow, it's releasing the bubbles that form on the inside surfaces of the can so they don't carry liquid up when the container is opened.

Re:I make beer... (1)

dragon-file (2241656) | about 6 months ago | (#45226507)

This sounds like it requires further testing. The setup: 5 identical cans, 4 shaken, one left unshaken as a control. Both the control and one shaken can are to be opened normally. The remaining 3 are to be opened as follows: Top tapping normal open, Side tapping normal open, and just a slow open method. Document results and we should find a conclusive answer to this problematic conundrum.

Re:I make beer... (5, Funny)

gstoddart (321705) | about 6 months ago | (#45226763)

This sounds like it requires further testing. The setup: 5 identical cans, 4 shaken, one left unshaken as a control.

Oh you'd need much more than that.

You need to test beer (light beer, normal beer, dark beer, American beer), sodas (clear, dark, diet, rootbeer). You could also test energy drinks.

You need to control for how cold the can and it's contents are. You could test for can size (is a tall can fizzier than a short can?). You could test the ratio of the can height to diameter. There's likely different types of pop-tops.

You might also need to determine the threshold for spontaneous can explosion where it's coming out even if you don't do anything. We'll need a paint shaker for this.

Hell, we might also need to do tests to determine if the likelihood is determined by how inconvenient it would be (critical need detectors and dress clothes).

I'm going to need a truckload of beers, sodas, a walk in fridge, a normal fridge, a bar fridge, several changes of wardrobe, two assistants, a steady supply of pizza, a lazy boy, a paint shaker, a monkey, 4K of cocaine, some LSD, several hookers, a high speed camera, a good internet connection and a really fast car.

The only thing I'm worried about is the bats. ;-)

Re:I make beer... (1)

mcgrew (92797) | about 6 months ago | (#45227869)

I knew I was going to get some laughs out of this link! Anybody have any mod points for this guy?

Re:I make beer... (1)

Pope (17780) | about 6 months ago | (#45227329)

Dude, you are complicating Beer Hunter waaay to much :)

Re:I make beer... (1)

mcgrew (92797) | about 6 months ago | (#45227927)

No, shooting beers (not to be confused with shooting beer cans, which is what they do in the country) was pretty popular back in the eighties, I remember seeing it lots of times... but never indoors. That would be pretty stupid (but beer can do that to you).

Re:I make beer... (1)

profplump (309017) | about 6 months ago | (#45226737)

Actually cans don't foam much. Many soda formulations include anti-foaming agents specifically to avoid the problem. So 3 is not so trivially false.

Also there are a number of other possibilities your list excluded. The most obvious being "the time that elapsing during the can transfer and top-taping are sufficient to squelch the foaming reaction; a can sitting untouched for the same period would also not foam".

Re:I make beer... (1)

gstoddart (321705) | about 6 months ago | (#45226855)

Actually cans don't foam much. Many soda formulations include anti-foaming agents specifically to avoid the problem. So 3 is not so trivially false.

I learned to do this in the early-mid 80's, and I doubt there was any of that. It was certainly a problem as a can could produce quite a geyser..

Also there are a number of other possibilities your list excluded. The most obvious being "the time that elapsing during the can transfer and top-taping are sufficient to squelch the foaming reaction"

LOL, I've been handed cans by people who shook them in front of me and successfully opened them if I was careful. But I don't recommend trying it at home unless you have a place you can make a mess in.

My friends were heartless bastards, so you had to assume all cans had been shaken just before you got them. This came out of simple self preservation.

Re:I make beer... (1)

umafuckit (2980809) | about 6 months ago | (#45229403)

I've used a technique much the same as yours but I leave out the tapping and just open slowly. Seems to work for me. I never understood why tapping should help.

Re:I make beer... (3, Informative)

OglinTatas (710589) | about 6 months ago | (#45226957)

You'll see that on plastic soda bottles (pop bottles, depending on your origin) the threads are broken by gaps. This is to allow you to do just that-- crack the top and let the pressure release. You may have to crack/seal it a few times to safely remove the top.
If the gaps were not there, you would have to unscrew the top much further to vent, and you would risk blowing the cap off and an ensuing fountain of foam.

Re:I make beer... (0)

Anonymous Coward | about 6 months ago | (#45227135)

Or you can just listen to the can, when you cannot hear bubbles popping any more it is safe to open.

Re:I make beer... (1)

dargaud (518470) | about 6 months ago | (#45227441)

Back to beer, if you pour a beer and the foam rises apocalyptically, a nice trick is that fat will change the surface tension and drop the foam. And the fastest access to fat you can have while sitting at a bar table or at home is... your own skin. So quickly rub a finger on your nose or forehead and dip it in the beer: it'll stop the foam dead on its track.

When I did it after pouring one of my beers with too much foam to a friend, he looked at me aghast, then pushed the glass to his wife: "this one's yours!"

Re:I make beer... (1)

mcgrew (92797) | about 6 months ago | (#45227959)

That's why some people put (yecch) salt in their beer. I don't think it's oils, I think it's the salt from sweat.

Re:I make beer... (2)

dwywit (1109409) | about 6 months ago | (#45229631)

Nuh - it's fat/oil. Collapses beer foam very quickly. Try this (and it's only in the interest of science that I recommend wasting a beer this way). Wipe a smear of cooking oil around the inside of a clean empty glass. Do it as far down the glass as you can get your finger, then tilt the glass and pour cold beer down the side of the glass to make sure the beer comes into contact with the oil. Put the glass down then pour cold beer the same way into another clean glass. Observe which one keeps the head longer.

There are some valid reasons to add certain salts/minerals to beer when brewing - some water supplies lack trace elements or salts needed by the yeast. I wouldn't recommend dumping plain ol' NaCl in there, though - it's a yeast growth inhibitor.

Re:I make beer... (2)

cayenne8 (626475) | about 6 months ago | (#45226177)

Ah... that explains it. I had become somewhat nervous about the beverages handed to me by my grade school son ever since he learned about that prank.

Well, an easy way to combat that...open every beverage he brings you, pointed back at his face...

Practical application (2)

Plazmid (1132467) | about 6 months ago | (#45225727)

Perhaps this could be used to figure out exactly how deadly limnic eruptions [wikipedia.org] are triggered.

Re:Practical application (1)

niftymitch (1625721) | about 6 months ago | (#45226139)

Perhaps this could be used to figure out exactly how deadly limnic eruptions [wikipedia.org] are triggered.

These can be lethal but it seems to me that a partial solution is possible.

What if one had the equivalent of an inner tube float with a longish dangling PVC
or equivalent pipe. A solar powered air pump can then push air as deep as the
power budget and mechanics permit. Down through a small diameter hose inside
the larger PVC pipe. The bubbles that then rise from the depth
can carry problematic CO2 saturated water from below not too different
than a percolator coffee maker. In some cases the resulting flow would become
self sustaining and either generate a warning or dissipate the risk.

Like I said... lethal but perhaps inexpensive to mitigate.

Re:Practical application (0)

Anonymous Coward | about 6 months ago | (#45226597)

Read the wikipedia page the GP linked to. It describes that exact mechanism and states that one has been in place since 2001, and two more were installed in 2011 on one of the lakes that has this problem.

It also notes that it's not so inexpensive, since the pipe degrades in the highly-acidic water at the bottom (which is acidic due to high CO2 concentrations) and has to be replaced frequently.

Re: Practical application (0)

Anonymous Coward | about 6 months ago | (#45227243)

Or perhaps rather than focusing in the effect they can focus on what causes some dick to do this to your nice beer.

Re: Practical application (0)

Anonymous Coward | about 6 months ago | (#45230653)

A child of Carie Nation

We have top men working on this (0)

Anonymous Coward | about 6 months ago | (#45225795)

Which men?

TOP men.

Old news (1)

gr8_phk (621180) | about 6 months ago | (#45225901)

IIRC the tap on top causes a low pressure wave starting from the bottom that allows the trapped gas to escape and form bubbles. This is not the first time the subject has been researched by a long shot.

Re:Old news (1)

NoNonAlphaCharsHere (2201864) | about 6 months ago | (#45226083)

the tap on top causes a low pressure wave starting from the bottom that allows the trapped gas to escape and form bubbles.

So, like some kind of resonance cascade, then?

Re:Old news (0)

Anonymous Coward | about 6 months ago | (#45226301)

So, like some kind of resonance cascade, then?

If that were the case, then it would be easily fixed the reversing the tachyon flow.

Re:Old news (1)

dragon-file (2241656) | about 6 months ago | (#45226545)

So, like some kind of resonance cascade, then?

If that were the case, then it would be easily fixed the reversing the tachyon flow.

I never thought I'd see a resonance cascade, let alone create one.

Re:Old news (1)

jm007 (746228) | about 6 months ago | (#45226149)

In any case, this can and swill be hoppily instilled into my own ongoing research. Ale let you know if I pint anything.

Re:Old news (1)

TooTechy (191509) | about 6 months ago | (#45226653)

Indeed. This sounds far more plausible.

Taping the top of the bottle would cause a volume of low pressure to be formed at the bottom of the bottle due to hydraulic action. This will cause large scale gas expansion.

An interesting experiment might be to create a partial instant vacuum in the fluid and see the results.

I saw similar results degassing brake fluid for my mountain bike.

Re:Old news (1)

Evil Pete (73279) | about 6 months ago | (#45228581)

Part of me keeps thinking that this sounds like a phenomenon that must have some industrially useful application but I can't think of it.

Like this is news? (1)

Impy the Impiuos Imp (442658) | about 6 months ago | (#45225975)

> A cloud of very small daughter bubbles are generated upon these collapses, that expand much faster than their mothers

Sociologists have long known that mothers who collapse typically have daughters that rapidly expand themselves.

Documentary that might help... (0)

Anonymous Coward | about 6 months ago | (#45225991)

I found a documentary that might help shed some light on the whole thing. It was done by some Australians back in the 1980s. Maybe it will help?

https://www.youtube.com/watch?v=Kp368iEcB78

Thanks blackberry (-1)

Anonymous Coward | about 6 months ago | (#45226029)

Thank you so much blackberry team. I was waiting this app. Its really great user friendly and smooth.

That's funny... (2)

Shoten (260439) | about 6 months ago | (#45226055)

...I always thought that the explanation for the phenomenon was, "The guy you're drinking with is a fucking douchebag."

This is also known as... (0)

Anonymous Coward | about 6 months ago | (#45226151)

http://en.wikipedia.org/wiki/Cavitation

Re: This is also known as... (1)

smaddox (928261) | about 6 months ago | (#45226703)

You've got the basic idea. It's a little more complex than simple cavitation, though, because the cavitation actually causes a runaway chemical reaction. So instead of getting short lives bubbles too small to see, the bubbles expand rapidly due to liberation of CO2 from carbonic acid, which in turn causes a pressure wave, which feeds back and causes more cavitation, etc.

This is science? (1)

bluefoxlucid (723572) | about 6 months ago | (#45226205)

Beer foam? Seriously?

It's well-known by homebrewers just how hard it is to get good head.

Re:This is science? (1)

SleazyRidr (1563649) | about 6 months ago | (#45226881)

I was about to reply saying that to get good head, you just need to apply the beer to the intended giver of the head. Then I realised that you specified _good_ head, and excessive alcohol consumption would impair the head-giving capabilities in much the same way as it impairs other capabilities, so it is still quite hard.

Re:This is science? (1)

Jmc23 (2353706) | about 6 months ago | (#45227947)

You've got it all wrong. Alcohol loosens up tight muscles, better head with less skill required.

Physicists and Beer ?!? (0)

Anonymous Coward | about 6 months ago | (#45226369)

Didn't anybody realize the explosive potential of putting those two things together?

Didn't work for me (0)

Anonymous Coward | about 6 months ago | (#45227063)

I've tapped many beer bottles together with friends to say cheers but that's never happened to me.

Now Do it in Zero gravity (1)

TheFakeMcCoy (1485631) | about 6 months ago | (#45228471)

Change a few things like the liquid with Dark Matter and the co2 as matter... explosive chain reaction. That's right our universe was created because some jerk in a cosmic bar tapped his or her friends drink.

Young Einstein (0)

Anonymous Coward | about 6 months ago | (#45229851)

Have none of you seen the movie Young Einstein? Watch it and it will explain everything, including how beer foam was developed in the first place. (Hint: it involved splitting the beer atom.)

Someone won a Nobel prize watching beer bubbles (1)

140Mandak262Jamuna (970587) | about 6 months ago | (#45230285)

The bubble chamber was invented by a scientist who was watching how the bubbles in a beer mug always come from the same spot. He won a Nobel prize for it. Imagine! A Novbel. For staring into a beer stein. http://en.wikipedia.org/wiki/Bubble_chamber [wikipedia.org]

Beer Foam Research (1)

lmnfrs (829146) | about 6 months ago | (#45230633)

Saw a presentation a couple years ago from Oregon State's beer professor. There's a lot of research being done on beer, and its foam, and some far more detailed than this story.

[google.com]https://www.google.com/search?q=site:oregonstate.edu+beer+foam+research

Science has so far been at a loss to explain... (0)

Anonymous Coward | about 6 months ago | (#45231253)

saturation and runaway nucleation?

Must've been those arts students coming up with names for things again.

College grant for beer research? (0)

Anonymous Coward | about 6 months ago | (#45231455)

Am I the only one who thinks that this was just a ludicrous ruse by a bunch of drunks college undergrads to score free beer?

Ah yes... (2)

Doghouse13 (2909489) | about 6 months ago | (#45231937)

...the old, hoary "science has been at a loss to explain.." hyperbole. Really? In reality, I suspect any number of science students could have made a pretty good guess on that one.
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