In this instructable I'll show you how to make a really simple kitchen accessory to keep your carbonated drinks fizzy for days (and more!) using only air pressure!

There's almost nothing more disappointing than a soda drink with no bubbles. So I thought, there should be a simple solution for this! But I couldn't find one online, so I made one! Some people told me this could be made for profit, but honestly, I don't want to do that :)

Hope you enjoy my project and make your own!

Supplies

I tried a bunch of different technique before posting this instructables - I made like 10 different versions of a 3-D printed air valves, but none were good enough. Eventually I decided to use a Schrader valve (the standard valve used in bicycles and cars). This turned out to be the simplest (and cheapest!) solution.

Here's a link to the valves I used (not an affiliate link). I tried a few other cheap ones, but these worked the best. Feel free to use any other valve though :)

You'll also need a suitable air pump (I didn't attach a link to this one, because mine broke just after a few weeks)

Step 1: Why Is the CO2 Escaping Only AFTER We Open the Bottle??

Have you ever wondered why carbonated drinks run out of bubbles after a while, but it only happens after we opened the bottle?

The answer has to do with air pressure inside the bottle! It turns out that by keeping the bottle pressurized, bottles cannot form and escape the liquid. This happens because dissolved CO2 takes less volume than CO2 in gas form, and by keeping a the bottle pressurized we're not letting those bubbles expand and form. So, the equilibrium state of the soda bottle is a state where the bubbles are dissolved in the liquid.

When we buy soda bottles they come pressurized (you can feel that the bottle is rock hard), but once we open them the pressure is released and the equilibrium state changes! Now, bubbles want to form and escape the liquid. It's not all bad news! We want this to happen, because otherwise we wouldn't get any fizziness when we drink it! The C02 would remain dissolved for ever.

But what happens when we want to keep the soda drink carbonated for a later time?

Well, if we keep the cap tight, bubbles can still escape the liquid! They keep escaping until the air pressure inside the bottle is high enough to stop them, but if your bottle has enough room in it, plenty of gas can escape the liquid before the formation of bubbles seize. This is why 90% full soda bottles remain carbonated longer than 50% full soda bottles do!

Solution to the Problem - Soda Companies Wished You Didn't Know This!

To stop the bubbles from escaping, we can actively pressurize the bottle (pump air to make the pressure higher) once we're done drinking!

This works like magic - one moment you see bubbles escaping the liquid (practically going to waste!) and a moment later (after you pressurize the bottle) the is no more bubble formation!

Step 2: Drill a Hole in a Bottle Cap

Drill a hole in the diameter of the air valve. It's better to have a hole that's a little too small than a little to larger. You can always widen the hole with a larger bit or just screw the valve in with some force like I did. I used a wood drill bit, but other drill bits would work as well.

Step 3: Attach the Air Valve

Screw the air valve in. Make sure the inlet is facing outwards (so you can attach a pump to it later!). Screw it as tight as possible to make sure no gases can escape.

Step 4: Pressurize!

Once the cap is screwed in, attach an air pump and pressurize. I have a hand-held pump that was built for bicycles and it worked great. Keep pumping until you see the gas bubbles stop forming! And that's it! You're done!

Keeping your beverages cold will also help keeping them carbonated for longer.

Step 5: You're All Done!

You're all done! The valve I used is supposed to be food-safe, but personally I don't trust cheap products that much. So, I just keep the bottle standing and the valve never touches my drinks :)

Hope you make your own cap! Let me know if you do, and if you have any questions feel free to ask!

If you liked my instructable you're welcome to check out my instructables page for more :)

See you soon!

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Thanks to all the people who have already supported me!!