How is loosening the cap and letting it go flat taking too long? Once it’s flat, it’s flat for all time. 
When I was in Europe (the first time, '73 or so), it was everyone’s habit to sprinkle a little salt into it. The head came down, but I don’t recall if it actually flattened the soda or not.
You can also buy it at Sam’s Club.
Eh, it’s not really forcing it out as it is kind of providing an outlet for it to come out. It’s the same idea as putting Mentos in Diet Coke. The sugar, being grainy, provides nucleation points for the CO2 to form bubbles in.
Pour the soda into a wide mouthed container to create a large surface area for the CO2 to escape and prevent the Mentos effect. Add clean sand, instead of sugar or salt, to provide nucleation sites for the CO2. Stir 'till flat and serve through a fine mesh strainer?
CMC fnord!
I’ve found that pouring any carbonated drink into a ceramic mug or cup provides a lot of foam and then a flat drink.
As Quartz sugested, pouring the drink from glas to glass is the recommended method by nurses to removed carbonation from sodas. I understand that flat Coke (or Pepsi) is sometime given to children to releive constipation (or some other stomach illness).
I’m talking about length of time from purchasing the drink to being able to drink it with no carbonation. Just loosening the cap would be effective if I bought a large number of drinks and planned to drink them later, but if I wanted to drink them ASAP with no carbonation, it looks like I’ll have to go with the pouring method. I do plan on trying it today…
Get a large glass, and fill it 1/2 way (or keep 1/2 of it empty, your choice).
Use one of those protein drink mixers to stir the heck out of it.
That ought to do the trick.
I feel your pain, here’s what I do with soda bottles.
I open it and take one horrible carbonated ship. This frees up room in the bottle, I then loosely place the cap on it and squeeze as much air out of the bottle as possible. I screw the cap on tightly and slightly shake it causing the released CO2 to expand inside the bottle and it’s shape to return to normal. I then open the bottle again and squeeze out the air and CO2 a second time.
Close the cap and repeat, this time usually enough of the initial CO2 has left the bottle andI can shake it pretty vigorously without worrying about it overflowing. Repeat as necessary, but I think at most I’ve had to repeat it only 3 times to get a perfectly flattened soda.
Works great and it only takes about 15 seconds.
Works horribly with canned soda tho…
The CO2 in solution is not very stable thus creating the fizziness we see/experience. A solid like sugar dissolves into a more stable solution, its been a while since chemistry for me but soda is a solution supersaturated with a gas. The gas precipitates out as bubbles. By placing something else into the solution you are forcing the less stable solution to precipitate out. This is why the mentos bomb works.
I dont know the name of this “binding strength of a solution” property but I’m sure its well defined and documented in a way that some of our doper chemistry gurus can articulate.
Whenever I need flat Coke or ginger ale for a kid with a tummy ailment, I pour it in a larger-than-necessary cup and then stir it vigorously for a few seconds (30-60).
Since weight-loss surgery that reduced the size of my stomach, I use a form of this for my beer, too. I pour it into an over-sized glass and stir it until it’s half flat.
I have the same problem. The way I solve it is that I microwave a glass of pop for a minute or so. That gets rid of a lot. Then I drink it. If I want it colder, I can add ice.
Whenever I get a can of diet soda in a restaurant that is at room temperature and pour it on ice, it loses a lot of carbonation, to the point I think it is too flat.
Does this happen with sugar soda?
If you have a container wide enough for a handheld eggbeater, that would be an enjoyable way to remove carbonation.
Or get one of those handheld drink mixers with a spinning wavy disk at the end of a shaft.
The easiest and most portable way to do it (in my opinion) is to use a straw. Just blow into the straw slowly and gently to make bubbles in the drink. It goes flat in no time and will work with bottles and cans without the need to carry around another recepticle in case you buy a drink while you are out.
Unholy fizzy zombie brains, Batman!
Do they make a Brains Nehi? Brain Crush?
Hijack: You know that Cola is contra-indicted for stomach flus and Diarhea, even though it was popular in the 50s onward with mothers? The coffeine forces even more fluid out of the body. I would recommend either flat mineral water (can you not buy non-sparkling mineral water in your country?) or even better, WHOs Oral Rehydrating Mix. / Hijack
This. Creating/providing nucleation sites is the key to getting the CO2 to come out of solution. When you first open a bottle or can, the beverage is super-saturated with CO2. The CO2 wants to come out of solution, but it happens slowly because the dissolved CO2 needs nucleation sites where this can happen. A nucleation site can be a free surface (e.g. the top surface of the beverage, or the surface of a submerged CO2 bubble), or a rough solid surface (e.g. grains of sugar or salt). In chemistry classes we were always advised to add boiling chips (basically small chunks of cracked porcelain) to test tubes of water that were being heated; the chips provided nucleation sites, facilitating a nice smooth boiling action rather than intermittent explosive steam generation that could shatter the test tube and spew hot water all over. This could work for the OP: add a teaspoon of boiling chips to the bottom of the glass before pouring in the soda. This would avoid altering the taste of the uncarbonated beverage like salt or sugar would.
Since the surfaces of submerged bubbles act as nucleation sites, another answer is to create more bubbles. The act of pouring the soda from a significant height, or transferring from one glass to another, or stirring it vigorously, or blowing air through a straw to the bottom of the glass, creates more bubbles by entraining air into the soda. This is why shaking a can/bottle of soda prior to opening it causes rapid escape of CO2 upon opening of the container: lots of pre-existing bubbles (from the shaking) provide a great many nucleation sites for CO2 to come out of solution as soon as the pressure is released by opening the cap.
So there are any number of ways to get the CO2 out of solution fairly quickly, but the challenge seems to be controlling the production of foam. That’s going to come down to how fast you pour it, or how much extra space you leave in your glass to accomodate the highest level of foam. Unlike beer, soda foam seems to settle down within seconds, so it’s probably not worth the trouble to explore solutions here.
When I’m in a hurry, I pour a half can into a glass then, using a glass of similar size, pour it back and forth from one glass to the other until all bubbles go away…takes 6-8 “pours.”