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Beer Shark Science

The Fascinating Science Behind Beer Foam 73

Posted by timothy
from the ok-now-explain-my-flickering-lights dept.
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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The Fascinating Science Behind Beer Foam

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  • by gstoddart (321705) on Thursday October 24, 2013 @01:18PM (#45225639) Homepage

    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.

    • by nytes (231372)

      It could be almost as much fun as mixing beer and guns.

      "Hey, guys! Watch this..."

    • by mcgrew (92797) *

      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 tappi

  • by fahrbot-bot (874524) on Thursday October 24, 2013 @01:20PM (#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.

  • by GoodNewsJimDotCom (2244874) on Thursday October 24, 2013 @01:22PM (#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.
    • by TheCarp (96830)

      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 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 d

    • by S.O.B. (136083)

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

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

  • I make beer... (Score:5, Informative)

    by dargaud (518470) <slashdot2@gd[ ]aud.net ['arg' in gap]> on Thursday October 24, 2013 @01:22PM (#45225721) Homepage
    ...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 ?
    • by jm007 (746228) on Thursday October 24, 2013 @01:28PM (#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... (Score:5, Informative)

        by gstoddart (321705) on Thursday October 24, 2013 @01:32PM (#45225889) Homepage

        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. ;-)

        • by SiChemist (575005)

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

          Link [youtube.com]

          • by gstoddart (321705)

            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.

            • by AvitarX (172628)

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

              • by gstoddart (321705)

                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.

                • by TheCarp (96830)

                  > 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

                • 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

                  • by SiChemist (575005)

                    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.

              • 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.
                • by gstoddart (321705) on Thursday October 24, 2013 @02:35PM (#45226763) Homepage

                  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. ;-)

                  • by mcgrew (92797) *

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

                • by Pope (17780)

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

                  • by mcgrew (92797) *

                    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).

                • Good news, it's already been done [straightdope.com].
            • by profplump (309017)

              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".

              • by gstoddart (321705)

                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 han

            • 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... (Score:4, Informative)

          by OglinTatas (710589) on Thursday October 24, 2013 @02:50PM (#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.

        • by dargaud (518470)
          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 you

          • by mcgrew (92797) *

            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.

            • by dwywit (1109409)

              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 longe

        • by steelfood (895457)

          You tap the bottom in the center. Don't pop the tab open too quickly. None of it will come out.

      • by cayenne8 (626475)

        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...

  • by Plazmid (1132467) on Thursday October 24, 2013 @01:22PM (#45225727)

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

    • 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 fl

  • 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.
    • 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?

    • by jm007 (746228)
      In any case, this can and swill be hoppily instilled into my own ongoing research. Ale let you know if I pint anything.
    • by TooTechy (191509)

      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.

    • by Evil Pete (73279)

      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.

  • > 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.

  • by Shoten (260439) on Thursday October 24, 2013 @01:42PM (#45226055)

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

  • Beer foam? Seriously?

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

    • by Bodhammer (559311)
      Speak for yourself!
    • 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.

      • by Jmc23 (2353706)
        You've got it all wrong. Alcohol loosens up tight muscles, better head with less skill required.
  • Sigh. The Tasmanians had all this figured out years ago. Haven't these guys watched Young Einstein?

    http://en.wikipedia.org/wiki/Young_Einstein [wikipedia.org]

    All you need is a chisel!

    • Spain. The smartest thing you can find here is the phones on people's pockets. And I speak as native.

  • to anybody who has taken acid and watched this happen?
  • 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.
  • 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]
  • 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

  • ...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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