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Q: Does tapping the top of a soda can stop it from foaming?

chow.com — A: Those who think so follow this logic: When you shake a soda can, little molecules of carbon dioxide bump into each other and form bubbles. These bubbles hang around on the sides and bottom of the can until you pop the top, at which time they shoot out, eager to escape to the lower air pressure outside the can

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  • Aindrea, on 11/15/2007, -7/+88It's quite simple really. Don't shake it.
    • STKD, on 11/12/2007, -0/+27Or shake the one behind the one you want to drink.
    • linagee, on 11/12/2007, -2/+20The real question is, will this one digg article prevent the average person from tapping their can? I think not. The tapping will just annoy the geeky folk that know the truth.
      • sgtbutterscotch, on 11/13/2007, -0/+7The article didn't exactly tell me anything about tapping my can, even though I don't do it anyway. Just because a couple spokesmen say that it doesn't do anything, doesn't really mean anything. I was expecting a mythbuster-like article.
      • FlyingSpaghetti, on 11/12/2007, -0/+3Great. Now we're going to have smug non-tappers amongst us.
    • blaze03, on 11/12/2007, -1/+11"Those who think so follow this logic: When you shake a soda can, little molecules of carbon dioxide bump into each other and form bubbles...Tapping the can prior to opening it, the theory goes, dislodges bubbles from the bottom and sides."

      Umm...I don't think anyone who actually does this follows that logic at all. Did they just make that up for the article?

      For most people, tapping seems to work because they're just delaying opening the can. I guess it gives you something to do while you're waiting, instead of staring at the can for 30 seconds.
      • alexgamerz, on 11/12/2007, -1/+6I used to tap on it and for the reason stated in the article. Now I will not be doing so though
      • OneLess, on 11/12/2007, -0/+5If you're tapping the can long enough to let the built up fizz dissipate, you've got more problems than exploding soda cans. OCD, for example.
    • Zalien, on 11/12/2007, -1/+2That works, but if you've already dropped it you can put just enough pressure opening it to hear it start fizzing, as long as you don't pop it open as fast as possible it should just fizz and then be safe to open.
    • pdxuser, on 11/12/2007, -0/+2"Tap at your own risk." Now there's a truism.
      (Seriously, I can't believe the comments are not full of knowing double-entendres about tapping one's can.)
    • esotericguy, on 11/12/2007, -0/+1Why does this scare me?
      http://img160.imageshack.us/img160/2240/capturevk7 ...
      • iguanapunk, on 11/12/2007, -0/+2The number of the beast is actually 616
    • aduzik, on 11/13/2007, -0/+1Apparently you're not familiar with the John Dorian three tap method. Three taps and the foam goes bye bye!
  • paulg2000, on 11/12/2007, -1/+35Or just wait for it to settle. You can be as nasty to the can as you want, but as long as you give it about 30 seconds to settle you'll be fine.
    Penn and Teller proved this on Letterman one time (too bad I can't find the video).
    • jun2san, on 11/12/2007, -3/+43Yeah, but Penn and Teller are also magicians.
      • terracottapai, on 11/12/2007, -0/+2They didn't use tricks, though.
        You can find this concept in their book 'How to Play in Traffic.'
        Basically the premise is that the magician acts like he can transfer carbonation from one can to another.
        You shake one can up, let it settle while you're doing your little hocus pocus, and open it. Nothing happens.
        Then, the other can you open but squeeze while you open it, spraying it in your subject's face.
        "Wow, the carbonation was so strong it crushed the can!"

        No trickery involved; the pressure actually dissipates.
    • nreynolds, on 11/12/2007, -2/+13you don't even have to wait. Just crack the pop-top a little bit, but don't really fully break the seal. The gasses will go out, and I've never once had a problem with it foaming. I don't know why it works, but it does.
      • Seifey, on 11/12/2007, -0/+34 "The gasses will go out"[...]

        I think that is why it works.
        • nreynolds, on 11/12/2007, -1/+3yeh... i mean.. i knew that, but i figured there was probably a smarter way of saying it and I'm too tired to try to think right now.
      • NoTiG, on 11/12/2007, -13/+1Actually its because of the exposure to the oxygen... by cracking it open only a little you expose it to much less oxygen
        • weeman43302, on 11/12/2007, -0/+6it's not the oxygen it's the change in pressure
    • puny_midget, on 11/12/2007, -2/+1You don't want too much of the gas to escape though, otherwise the drink becomes flat. Ideally, you would want to cool the can before opening it as that will increase the solubility of the CO2 gas. Having all the gas dissolve will make it taste better and also more difficult to 'sabotage'.
  • pintomp3, on 11/12/2007, -0/+92i think the reason people think it works is because (assuming they are tapping lightly) all they are really doing is delaying opening while they tap.
    • thebillgonadz, on 11/12/2007, -0/+3Yeah, I just look at it as a habit.
  • ambiguus, on 11/12/2007, -2/+11nerdygirl.com did a little experiment with this and a bunch of different conditions: http://www.nerdygirl.com/sodascience.php
  • RegularJohn, on 11/12/2007, -6/+10Ok, this was a stupid study ...
    • mlostracco, on 11/12/2007, -0/+5Stupider is people believe that tapping a can with their fingernail will prevent a shaken can from foaming.
    • sgtbutterscotch, on 11/12/2007, -0/+1...this was a study? I must have missed the figures and stats.
    • h4mx0r, on 11/12/2007, -0/+2All in the name of SCIENCE!
  • Br0wn, on 11/12/2007, -0/+26FTA: “We are not aware of any impact that tapping on the top of a can before you open it has on fizzing over,” said Scott Williamson, a Coca-Cola spokesman in Atlanta. A counterpart at Pepsi concurred, though neither was quite able to explain why the tapping doesn’t work."

    What a groundbreaking story, can't believe they actually interviewed a spokesman for proof. Next we see if someone wishes you Good Luck, will it actually bring luck?

    Also be advised: Tap at your own risk.
    • mcduckov, on 11/12/2007, -0/+1I don't drink anything carbonated but it seems to me that tapping the top will cause any drops of liquid clinging to the top of the can to be dislodged. This may have the effect of causing there to be less liquid spraying out with the CO2.
  • royall64, on 11/12/2007, -7/+3I've never heard of tapping your can like that, and I don't see how it would work. If you shake a can, you can't unshake it.
    • najdorf, on 11/12/2007, -0/+6Heh, you can but it's entropically unlikely.
  • truegodofwar, on 11/13/2007, -17/+92Lol, What happens when you *don't* tap the top of your soda...
    http://youtube.com/watch?v=eBGIQ7ZuuiU
    • goldfishwish, on 11/12/2007, -3/+5that made my whole day better! i laughed so hard i cried.
    • kbeeveer46, on 11/12/2007, -1/+36OMG, I hate you
    • GvnMcCld, on 11/12/2007, -1/+39That was executed flawlessly.
    • cub404n, on 11/12/2007, -6/+0thnx alot! ....Not
    • Nekiruhs, on 11/12/2007, -2/+3God! That was so perfect. Respect +1
    • travis712, on 11/12/2007, -1/+7Well executed, sir. It appears I have fallen victim of the shameless embarrassment of the double R.
    • najdorf, on 11/12/2007, -3/+6Didn't work, I already memorized all the GET parameters for his videos.
    • N256, on 11/12/2007, -1/+2Classic digg magnet.
    • je12u, on 11/12/2007, -2/+2Logged in just to dig you up
    • QueEsAmor, on 11/12/2007, -2/+1I've memorized the URL for that. I'm immune to the RickRoll!
    • MalDON, on 11/12/2007, -0/+3And I fell for it. Perfect. Was not expecting it!
    • PopularNerd123, on 11/12/2007, -3/+2LOL i got rick roll'd
    • hypnotoad32, on 11/12/2007, -0/+2Don't encourage him, Barth.
    • DThatsMe, on 11/12/2007, -0/+1Nice work!
    • castevens, on 11/12/2007, -1/+1touche, sailor.
    • neutralmind, on 11/12/2007, -0/+1Let me quote this from the video, "I'd hit it, twice that is.."
    • Nineless, on 11/12/2007, -1/+1Damn it. Well executed though, my hat off to you.
  • Albo23, on 11/12/2007, -10/+1No. Know how about you do some studies on cancer or a different energy and not on ***** soda which is bad for you anyways. (Waits for study saying soda is good for you. -.-")
    • Seifey, on 11/12/2007, -0/+9Yes, because the people doing 'soda foaming' tests are the same people that should be looking for a cure for cancer.
  • macweirdo42, on 11/12/2007, -9/+11You know, I've always done this, but I never had any reasoning for it beyond the fact that it seems to work. I never even tried to come up with a theory. It's like blowing on an NES cartridge... you never really know why it works, you just know that it works.

    I will say I don't buy the "extra time" theory, though. I tap 15-30 seconds tops, and I've never seen a soda settle that quickly on its own (by which I mean that generally when I open a shaken soda after just 30 seconds withou tapping, I usually get a faceful of soda).
    • charlie55, on 11/12/2007, -9/+7it doesnt work, you are dumbass.
    • FadieZ, on 11/12/2007, -1/+6Probably something to do with dust interfering between the cartridge and the console.

      I just realized something though. How did a bunch of young children figure out that blowing dust out of the cartridge would jumpstart the game?
    • acdcfanbill, on 11/12/2007, -0/+1I always 'tap' by lifting the tab slightly and letting it smack back onto the top of the can, thus barely breaking the seal and letting the pressure equalize a touch before fully opening the can, I find this works well usually.
  • chingy1788, on 11/13/2007, -2/+39http://www.youtube.com/watch?v=ImvweQviu2o
    tapping method in action
  • syuusuke, on 11/12/2007, -0/+18get mythbusters on this
  • speedyrev, on 11/14/2007, -1/+35If you tap it more than three times, your playing with it.
  • crapmatic, on 11/14/2007, -0/+35If something taps back, do not open the can.
  • Subterfug, on 11/12/2007, -2/+8I used to tap, then I stopped drinking sodas altogether.
  • skinny01, on 11/12/2007, -0/+3All you have to do is crack the top just enough so the air leaks out. Once it's finished and you can squeeze the can, then you can just open it up all the way
    • mlostracco, on 11/12/2007, -0/+1While we're kinda on the subject, I know people who think that squeezing the 2-litre bottle before putting the lid back on will prevent the pop from going flat, when it's actually the opposite—the more space left to expand, the flatter the pop.
  • zerozidane, on 11/12/2007, -0/+13You're obviously not familiar with the John Dorian 3 tap method.
  • chugger1992, on 11/12/2007, -1/+2I just do it out of habit.
  • chudgoo, on 11/12/2007, -5/+6OMFG. This has been with me ever since about 6 years old.
    The act of tapping is nothing more than ritual. The "it makes the bubbles sink" argument is just ignorant.
    PHYSICS PEOPLE!

    PHYSICS! (you know, real science)
    • AttilaD, on 11/12/2007, -0/+1Use some fizzics to prove to me that it DOESN'T work then. Quoting Coke and Pepsi spokesholes with a degree in business ethics and psychobabble isn't going to convince me. For now, I'll accept the admittedly completely circumstantial evidence that every time a can of soda has exploded on me has been a time that I did not tap the top.

      Tap == !Asplode
      Asplode == !Tap
      !Tap == (Asplode || !Asplode)
  • charlie55, on 11/12/2007, -1/+5i have never known anyone stupid enough to think this would work. it is absurd on the face of it. you dont agitate a can of coke to relieve the pressure. you open it and hope for the best.
  • chubbybubba, on 11/12/2007, -10/+3This article is insane. It ABSOLUTELY works! Try it. The reason why this works is similar to the way antacids work to alleviate gas pain in the stomach. When someone shakes a can of soda the pressure builds up because of the tiny bubbles (foam). The structure of the bubbles necessitate a greater volume and thus pressure builds up. When one taps the top of the can the structure starts to break back down decreasing pressure. In the stomach when these same bubbles build up, antacids help break them back down. This is one of those stupid things that anyone can just try. I've bet people that I could open a soda that's been shaken like hell, even dented. Don't believe me, just try it. (Stupid article!)
    • wolfkeeper, on 11/12/2007, -1/+4Unfortunately for this theory, people have connected a pressure gauge to a carbonated beverage bottle; left it to stand till it stops bubbling, and then shook it, with the pressure gauge still connected- the pressure stays the same. You get lots of small bubbles, yes, but that doesn't change the pressure at all.

      What causes the foam is the expansion of those small bubbles; not any increase in pressure; any more than the foam in your kitchen sink if you use detergent is at higher pressure.
      • chubbybubba, on 11/14/2007, -0/+1Look, you are absolutely nuts. We can agree to disagree but in the real world when you shake a can or even a 2 liter bottle you can PHYSICALLY feel an increase in pressure of the can (or bottle). Try this. Take a can of carbonated beverage and poke a hole big enough for some of the liquid to escape. You can even dent the can to facilitate loss of fluid. Then when about a quarter of the fluid is gone cover up the hole with your thumb and shake the can. The can Physically (magically in your case) will re inflate because of pressure increasing as you shake it. (this is David Blaine's can trick by the way.)
  • MrPapaMan, on 11/12/2007, -6/+1Actually if you do a hard "flicking" motion on the side of the can and do it all around the can it is supposed to help. It's supposed to help all the gas rise to the top before opening.
  • bradcrc, on 11/12/2007, -6/+1someone told me that tapping the *Bottom* of the can helped reduce bubbles.

    I tried it a few times, and it worked, so I'm convinced. Though I haven't had a reason to do it in years, so I'd forgotten about it. I'll have to do my own experiments next time I remember.

    as someone suggested, it may be nothing more than the extra seconds before opening the can, but it definitely seems to have worked in my experience.
  • RollFizzlebeef, on 11/12/2007, -1/+21Enough of you libtards and your "science".
    I pray to Jesus, and He calms down my soda every time.
  • tbunreal, on 11/12/2007, -2/+0"tap at your own risk"
    -always use protection
  • imcybersmart, on 11/12/2007, -2/+0no
  • timjim31, on 11/12/2007, -1/+7so they're comparing what two spokesmen say to a university department of physics?
  • Lazyboy0172, on 11/12/2007, -4/+1I was always taught the flick the side thing, to shake the bubbles off the side and let them float to the top, so when you open it the gas is on top when it escapes, bringing no soda with it.
    • p3ngwin, on 11/12/2007, -0/+0yes EXACTLY!
      i smack the the can down down on it's base to make the bubbles the were on the sides all go to the to. thus when you open the can, there are a "normal" amount of bubbles on the sides, and the gas at the top escapes WITHOUT bringing a load of liquid out with it.

      think of popping a balloon UNDER water.
      the gas wants to rise so fast it carries water ON TOP of it (friction) and bring the water into the atmosphere. same thing with the bubbles in soda. if you agitate it, when you open it, the bubbles want to come out from UNDER the fluid that they bring fluid with them into the atmosphere.

      the little taps that people talk about here that morons do, is idiocy. it takes a good bash like flicking the sides, or like i do bashing the bottom.

      to qualify this, see if you can find a soda brand that has the clear can (like TAB CLEAR all those years ago), or maybe just pour some soda into a tall glass. now lightly tap the top and see if the bubbles rise to the surface.......it won't be enough. yo have to BASH the *****!
  • cerberes, on 11/12/2007, -1/+0As bottles are being filled its all about keeping it gentle. The soda fills the can along the sides of the can and just before its release from the filler a small valve opens to let off the pressure. The can then goes to the seamer which puts on the lid.
  • dimplemonkey, on 11/12/2007, -1/+1well thanks for putting this urban legend to rest. Time for bed...
  • rocknroll4ever, on 11/12/2007, -2/+0 WANT TO TRY SOMETHING DIFFERENT ? TRY TAPPING ON A CAN OF BEER !!! MAKE SURE ITS NICE AND COLD THOUGH !!
  • dwninjungleland, on 11/12/2007, -2/+1I'm positive this works. I actually invented this technique. !!!!!!1
  • jameshighmore, on 11/13/2007, -1/+5Oh man. Rick Rolled twice in one Digg session.
  • wannapiece, on 11/12/2007, -0/+4This proves nothing! Other than that two spokesman think that they are scientists
  • xkilleddestinyx, on 11/12/2007, -1/+1Dugg for being the most useless article I've ever seen. One) this is common knowledge the more you shake a can the more it fiziz and two) don't we have better things to do then find ways to de-fiz a can? It's called put it in a fridge or freezer for a bit and your problem is solved or wait to open it.
  • JCritter, on 11/12/2007, -2/+4I've done this for the past 40 years. I've shown people that it works. Take two cans. Shake both of them. Tap the top of one and open it. No foam. Open the other and it foams all over the place. I don't care why. I just know it works!
    • rocknroll4ever, on 11/12/2007, -4/+0 I DIDNT KNOW THEY MADE CANNED SODA 40 YEARS AGO !!
      • dethsesh, on 11/12/2007, -0/+3they actually made canned soda 70 years ago, whats your point?
  • ujaknak, on 11/12/2007, -2/+0I once heard that if you squeeze the can/plastic bottle for a min. or so the pressure from squeezing will force the gas back into liquid. I've tried but pretty sure it doesn't help/hurt but it can't be as bad as flicking the top with your fingernail causing more release of bubbles and a sore fingernail.
    • p3ngwin, on 11/12/2007, -1/+0you know people that think they have the strength to compress gas into liquid??

      ha ha now i've heard everything
  • Richandler, on 11/12/2007, -3/+1I always tapped the side. That always worked better. It's like opening a jar. You wouldn't bang on the top by tap the side.
  • cvrefugee, on 11/12/2007, -3/+5Mr. Wizard taught us that this works. Why don't you guys go out and actually try it?
  • ithejosh, on 11/12/2007, -0/+1Uh yeah. I just barely open the can and let the gas and stuff seep out little by little and drink the soda taht comes out.
  • rickbauls, on 11/12/2007, -1/+1Still no cure for cancer
  • Rell812, on 11/12/2007, -1/+4I wish I could digg this story 500 times.
  • SomeCallMeBruce, on 11/12/2007, -1/+10I always knock on my fridge before opening it. Keeps the milk from exploding. Hey, I've never had an exploding milk yet.
    • ck314, on 11/13/2007, -5/+1that is definitely the dumbest thing ive heard all day
  • erobinson90, on 11/12/2007, -0/+0part of me wishes i was in third grade again and had to do a science fair experiment. drinking soda and solving one of life's mysteries
  • bmunichman, on 11/12/2007, -2/+1Look, its not that hard to understand. Tapping a can that has been shaken has done _nothing_. When you shake up a can of soda the small pocket of air in there gets mixed around and make small bubbles in the liquid. Bubbles so small that they don't immediately rise to the surface, they get moved around for a little while by the fluid currents. If you let the can set for a while, these little bubbles eventually make their way to the surface. If you open the can immediately, two things happen. One, the decrease in pressure makes the bubbles within the liquid expand. Two, because it is carbonated (meaning can has been pressurized with CO2, which becomes dissolved in the liquid in proportion to the pressure of carbon dioxide above the liquid), the pressure drop makes the CO2 in solution want to escape. The bubbles from shaking provide nucleation sites where the CO2 can spontaneously leave the liquid. This makes a lot of gas within the liquid, which expands and blows out the opening. Tapping will do nothing except take up time so that the little bubbles can settle to the surface.
  • guitarmaniac, on 11/14/2007, -1/+2What does work is opening the can half way so that the pressure is released but the can is not fully opened. Then you can open it all the way and there's no fizz
  • Pic0, on 11/12/2007, -6/+1i think time spent studying a soda can could be better spent finding a cure for AIDs or cancer...
  • guitarplayer673, on 11/12/2007, -0/+1A fairly pointless story, but now I know I've been right every time I've argued about this.
  • pixel, on 11/12/2007, -1/+11 - Shake the can
    2 - Take a quarter (or any metal object) and tap the TOP of the can firmly for about 5-10 seconds.
    3 - Open can with no mess
  • Shempo, on 11/12/2007, -2/+3Ive always tapped the can, more out of habit than anything. No harm done in doing it, and I haven't had a can accidentally explode on me in a long time. What I don't understand is the people that DONT tap the can and get all angry about it. Literally every time I do it in-front of people I get one person who feels the need to show his super intellect off.

    "That doesn't do anything you know, and you are an idiot for thinking it does. I am a better person"

    Ill continue tapping my can, thank you. Enjoy your sticky fingers.
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