silly carbonation question

I've been wondering for a while and figure I'll just go ahead and ask

If I force carb some root beer in a 2 liter, I can expel the air then stick it on CO2 @ 40psi, disconnect and shake. Connect, disconnect, shake. This is considered a good thing and the exposed liquid surface area will absorb the co2 thus carbonating the beverage. Eventually it just won't take any more co2 even after shaking. At this point I can open it up and try what I just made.

So my question is - if I shake a 2 liter of pepsi then open it, why does it explode, but my homebrew force carbed soda doesn't even if I just got done shaking it for the last 20 minutes on and off?

maxx233 said:

I've been wondering for a while and figure I'll just go ahead and ask

If I force carb some root beer in a 2 liter, I can expel the air then stick it on CO2 @ 40psi, disconnect and shake. Connect, disconnect, shake. This is considered a good thing and the exposed liquid surface area will absorb the co2 thus carbonating the beverage. Eventually it just won't take any more co2 even after shaking. At this point I can open it up and try what I just made.

So my question is - if I shake a 2 liter of pepsi then open it, why does it explode, but my homebrew force carbed soda doesn't even if I just got done shaking it for the last 20 minutes on and off?

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My guess is that the commercial soda is more highly carbed, so shaking it causes the co2 to come out of solution when opened, making a soda geyser.

I carb mine @ 50psi in a two liter bottle and I get a geyser but if your getting good carbonation and no geyser I'd be happy to know what your doing
I also put mine in the freezer to get it as cold as I can short of freezing so it absorbs co2 better

YooperBrew said:

My guess is that the commercial soda is more highly carbed, so shaking it causes the co2 to come out of solution when opened, making a soda geyser.

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Wouldn't the vessel/2 liter bottle ultimately reach equilibrium though? If they could carbonate the liquid at 50-60 psi, put it in the bottle, and then fill the headspace at 30 psi - but have the co2 remain in the liquid at the same pressure... Then I could see why shaking it would release it. But my understanding is that the co2 would equalize pressure after sitting on the shelf for a while.. thus the liquid and headspace would be the same, and shaking it would neither absorb more co2 into the liquid, nor extract co2 out of it?

@ob111 - if you're getting geysers, I'm honestly not sure what I'm doing special/wrong <chuckle> I carbonate at 40psi because it's the highest my regulator will turn because there's a nut on it preventing it from going a notch higher that I need to take off. Once I do perhaps I'll have to try cranking it to 50 and seeing what happens.

it could be the extra 10 psi
I do find the more sugar in the soda the more foam ie cream soda
that could be part of it carbonated water doesn't foam up but thicker liquids do
just for kicks I'd like to carb up a 500 ml bottle of milk to see how thickness affects the co2 release
I also have that damn lock nut on my reg I was going to cut it off cause mine maxes at 50
I noticed that there are threads on the reg housing. I was thinking that if I can turn that in the stem will be able to have more stroke
when I get around to it I'll post the outcome
it seems everyone's reg maxes far below what the gauge offers

well it was easier than I thought
I can now max my gauge at 60 psi
I took step by step pics
and it took about 5 mins
I'm not sure if the admins or mods would have a problem with me posting them
and giving detail


to the mods and admins
please let me know if it is ok to post the pics
and an explanation to what I have done
for my model of regulator
with safety tips of course
it might make a good sticky

I've got one of those carbonator caps, and they say not to carbonate past 40psi. I have my regulator set at 39.9. I can achieve commercial level carbonation, but it is pretty fleeting (usually have to recharge whatever is being carbonated within 48 hours)

Has anyone else gone past 40 psi with a liquid bread carbonater cap?

Just go to a car parts dealer and get a tire valve stem for mag rims the ones to that have a nut to sandwich the two rubber washers and drill a close tolerance hole in a 2l bottle cap
the trick is to secure the cap on a bottle then drill so you don't damage the pop caps plastic seal
then just slide it in from the bottom with one rubber washer, then put one rubber washer on top followed by the backing plate then screw the nut on and snug it on
I've had one at 72 psi with no leaks that's far above what I carb at

maxx233 said:

@ob111 - if you're getting geysers, I'm honestly not sure what I'm doing special/wrong <chuckle> I carbonate at 40psi because it's the highest my regulator will turn because there's a nut on it preventing it from going a notch higher that I need to take off. Once I do perhaps I'll have to try cranking it to 50 and seeing what happens.

Click to expand...

Rather than working on your regulator, it would be easier to chill the beverage and then add the CO2. You'll get roughly the same amount of carbonation in the drink using 18 PSI at 40 F as you will using 40 PSI at 74 F. So put it in the fridge, and then pull it out and pressurize it while it's cold, then stick it back in the fridge. You may have to repeat a few times to get it saturated, but if you want to increase the pressure, you have plenty of room to do so without modifying your regulator.

Does anyone know what the typical level of carbonation is for most commercial soda (how many volumes of CO2)?

MedsenFey said:

Rather than working on your regulator, it would be easier to chill the beverage and then add the CO2. You'll get roughly the same amount of carbonation in the drink using 18 PSI at 40 F as you will using 40 PSI at 74 F. So put it in the fridge, and then pull it out and pressurize it while it's cold, then stick it back in the fridge. You may have to repeat a few times to get it saturated, but if you want to increase the pressure, you have plenty of room to do so without modifying your regulator.

Does anyone know what the typical level of carbonation is for most commercial soda (how many volumes of CO2)?

Click to expand...

Yeah, I keep mine in my kegerator when I'm carbing at 40psi - I just wish I could get that extra 10psi without that darned nut. As far as typical commercial soda levels I believe are 3-6 volumes, mostly 5-6.

OB111 - please post! I'd be glad to read a successful story, otherwise I'm just gonna get creative myself

How low are you able to get the temp on your kegerator?
If you are doing a 2 liter bottle, why not stick it in the freezer. At 32 F, 40 PSI will get you 6 volumes. Of course I don't know what happens to a carbonator cap with that much pressure when it warms up - could be messy.