Originally Posted by Pie_Man
If the gravity is stable over a 2-3 period, it is safe to bottle. ...
I think this rule of thumb is ok as long as you're within ballpark of where the FG ought to be based on what the expected attenuation of the yeast strain is.
I think I just dodged a bunch of potential bottle bombs - I recently had a Hobgoblin clone using Wy1187 Ringwood staying at about 1.023 for several days and thought I might well have mashed a bit high so went ahead and bottled them primed to 2.5 CO2 volumes.
Couple of days ago I was lookng through the PET bottles of that beer I keep to monitor pressure levels and the plastic caps were actually ballooning out as domes when they should be roughly flat!
So I proceeded to let out the pressures gradually by (refrigerating them bottles first) unscrewing the caps by tiny amounts and letting CO2 out, stopping when the beer started to fizz, resting, and repeating a few times until they seem safe.
With crown capped glass beer bottles of the clone, I put a thin coin over the cap and use a bottle opener to prise the caps off by really tiny amounts until CO2 starts to be released, and again having to stop (Ed. using bottle capper to securely recap
), wait for beer to settle and repeat several times. With one of these bottles, as soon as I touched the cap it just popped off and gushed for some while.
I have a bunch of champagne bottled bottles of the clone to deal with next as well.
I also checked the SG of some of the fizzed out beer (which tasted quite good but had what must be a fair bit of carbonic acid bite to them) and it seems to be at 1.012.
So that might be 11 gravity points that carbonated in the bottles which according to BrauKaiser here
each grav point equates to 0.5 CO2 volumes so the bottles may have been primed to 5 + 2.5 volumes!
I'm now paying more attention to the expected FG of a beer in Beersmith - make sure the yeast in the recipe has the right average attenuation according to Wyeast/etc, and vary the batch volume until the predicted starting SG matches what is actual measured and the Final Gravity Estimate is what to aim for.
Ed. In other words, I must have had a stuck ferment originally.