Overcarbonation when bottle aging

This seems bizarre:

My typical process will be to keg most beers, and if I really want to get something from the fermenter to keg before a keg is freed up, I will bottle off the remainder of the previous keg with either a beer gun or a bottle wand, and rotate in the new beer.

In a few instances, I have noticed the beers have become OVERCARBED after aging in the bottles. My first thought would be infection, but I tasted a bottle of my 80/- from 9 months ago last night, and despite violent “psst” when opening and baking-soda-in-vinegar-like carbonation in the glass, the beer tasted fine once it degassed a bit.

One other detail: i will usually quick/blast carb for 30-45 seconds at 30-35 psi when kegging a new beer. The only other thing I could think of is when I carbed the 80/-, it actually may have been overcarbed, as at that time, I was turning psi down to 2-3 for serving (and bottling in this case).

Wow, I’ve stumped the boys from the great white north. Wll have to take this one over to stackexchange and put a bounty on it…

You’re bottling off a keg and the beer is carbing more in the bottle and there’s no infection? The 30-45 second 30psi “blast” shouldn’t be a factor (I leave most kegs at 30psi for 24 hours and they’re not even close to carbed).

Is it possible the beer did not fully ferment in the primary and fermentation is finishing in the bottle?

[quote=“Pietro”]

The only other thing I could think of is when I carbed the 80/-, it actually may have been overcarbed, as at that time, I was turning psi down to 2-3 for serving (and bottling in this case).[/quote]
Thus your problem. Bottling at this point won’t lower the volume of co2 by much.

Is the level of carbonation this high if you open a bottle immediately/soon after bottling? Or are they fine at first only to become overcarbed later. I think it would be very difficult to carbonate a beer to the point of gushing using a beer gun.

They are fine at first, but then the beer seems to get increasingly carbonated as I age the bottles.

I understand that there should theoretically be a fixed amount of CO2 in the bottles once capped, again, unless an organism is making more of it. But that would likely manifest itself in the taste of the beer.

Sometimes when I would keg in the past, I would need to turn the SERVING psi way down after blast carbing it, which could mean that its a little overcarbed from the start. But if it tasted fine/had normal carb in the glass poured from the keg (and when it was first bottled), I am truly at a loss.

Right, but I’m also rolling the keg for those 30-45 seconds. Have had good results doing it this way in the past, but maybe its time to try a slow roll carb.