Half full keg quick carbonation theory

[Ari]

Hey y'all!,
I've been on here about a year and I don't think I've made a thread yet. I have a double birthday party tomorrow and I'm not hoping to get advice before then, but I do want some perspectives on this. I do 2.5-3 gallon batches and I recently started kegging. I keep them about 38 degrees and set them to 12 psi for a week and it works perfect. I was out of town until today however and I need to do the dreaded unreliable overnight carb thing. I did notice though last time that if I put in 12 psi, unhooked the gas, shook it and hooked it back up, the gas would flow back in because some co2 was absorbed into the brew. I have read all the force carb method threads and articles and I got to thinking. Couldn't I just do the hook/12psi/unhook/shake over and over and get to the perfect psi pretty soon? It makes sense to me that there is going to be a lot more surface area in the half full keg especially when shaken. A full keg has a few inches of headspace and a half full keg has...half the keg of space(co2) and when shaken, a lot more suface area/sloshing/mixing/contact than the full keg. There's less liquid to absorb co2 and more co2 than a full keg at the same pressure. I also thought, if this is tedious I could try it at 15psi or even 20 and every time I hook back up start at 12psi to make sure its getting all the c02 mixed in and that gas is still entering the keg at 12psi. I feel like im onto something that could be a little more practical than hoping that you pull out a 30psi load before you pass the desired carb volume. If it's only at 12psi, shouldn't it never over carb regardless of shaking amount? That is a question that I've been wondering as well and if the answer was yes, this method seems like it could be more practical than the typical fast carbing method
I know it's a bit much but I think it might be usueful information if we could figure this out.
Thanks for reading/skimming!
-Ari
I'll make sure to tell you what happens, probably friday.

 

[JuanMoore]

As long as you leave it at the serving pressure, you can shake it as much as you want with no risk of overcarbing, and this is a relatively common method. Most people who do this don't disconnect the gas line, they simply set it to serving pressure and shake. I suggest only doing this if you have a working check valve in your gas line though, to help prevent getting beer in the gas line or regulator. I'm not a fan of the method, but that's just personal preference. I've found the beer to have a bit of a carbonic acid bite, and any sediment that settled out while the beer was chilling will be stirred back into solution. On the rare occasions I don't have the time to use the set and forget method, my preferred carbonation method is using a carb stone. If I didn't have a carb stone, I'd put the chilled beer on 30 psi for ~36 hours and then reduce to serving pressure, with no shaking.

 

[BigFloyd]

+1 on no shaking on a batch you want to serve soon unless you desire cloudy brew.

 

[Ari]

It came out alright. I tried shaking it for a while, but it didn't really get better at 12 or 15 psi so I ended up cranking it up to 30 over night. Wasn't bad but I'll get a good week or two in next time