Overcarbonation caused by bottling colder beer?

[foxyaardvark]

I bottled a spiced porter about 4 weeks ago. Now I have overcarbed bottles that make an explosive "pop" sound when I open them after refrigeration and mild gushers if I open them at room temp. I used about 4 oz of priming sugar for a 5 gallon batch. The beer tastes fine, just really over carbonated. Doesn't taste infected I don't think. I stirred the priming sugar very well before bottling so I don't think it is uneven distribution. One thing I did notice this time was that the beer seemed to have a fair amount of residual CO2 from fermentation when I bottled. Also, it was slightly colder than room temperature, as I had been storing it in a swamp cooler with water. My question is: could the over carbonation I'm experiencing be caused by bottling colder beer and not adjusting the amount of priming sugar to take this into account? Should I try to vent my bottles and recap? I have ez cap bottles. I don't want bottle bombs.

Note: I had stable FG ratings for two days at 1.015 before bottling.

 

[hlm123]

The warmer the beer gets the more CO2 escapes, so if it was relatively cool the whole time there will be carbonation, like you noticed. That's why software for calculating the priming sugar will ask what the highest temperature was that the beer reached. I'm not sure if that should include while fermentation is still active, since later it can cool down and ferment more, which means more CO2.

 

[Kealia]

The temp at bottling isn't really a factor - it's the highest temp you reached during fermentation that matters. All of your beer will have some residual CO2 in it with the amount varying based on temperature.

The higher your temp got during fermentation, the less residual CO2 you will have in suspension. So, a beer fermented at 62 will have more residual CO2 in it that a beer fermented at 68. As the temp goes up, the CO2 gets released. In the case of cold crashing before bottling (for example) you don't get that CO2 back so when using a calculator you use the highest temp achieved.

That all being said, I wouldn't expect you to have severely over-carbed beer because you fermented a few degrees colder this time around.