Bottling cold (prime sugar, carb & gas)

[Pyg]

Understanding bottling carbing, temp and prime sugar.

I tend to Cold crash a few days prior to bottling.
Prior to bottling I use the prime sugar calculator, usually on brewers friend or others on the interwebs.
When the calculator asks me for the temp of the beer, I enter the current temp.
the Prime sugar calc tells me to add more prime sugar than if it was warm.

I am under the assumption that there is more gas trapped in cold beer than if it is sitting warm, since gas escapes warm beer over time.

I know on occasion I have added the amount of prime sugar as advised by the calculator and months later had way too much carbonation in my bottles.

Should I be using the temp of the beer at the time I bottle (after cold crash) or the temp the beer fermented at?

 

[jbunton]

I use the temp I will be conditioning the bottles at not the current temp and it's worked out great for me.

 

[microbusbrewery]

Use the temp you finished primary fermentation at, before cold crashing. So say you did your primary fermentation at 67F, use 67F.

At a given temp a certain amount of CO2 will remain in solution. The calculators do a best estimate of what's still in solution for a normal* fermentation at the given temp. Once you start cold crashing the yeast go to sleep, so they're not producing additional CO2. Unless it's in a closed system under pressure, the volumes of dissolved CO2 will be the same (or close enough) at the end of primary compared to after cold crashing.

* = By normal, I mean a primary fermentation less than a month. If you were to bulk age like you'd typically do for a sour beer, it could be completely still by the time you're ready to package.

 

[Pyg]

Thanks for info.
I guess using your information I may have under-carbed a little.
The difference between 68 & 60 was
.33 oz (3.6 to 3.3)
Which I guess I would rather have slightly under carbed than over carbed.
Just had to dump my last few summer smashes because they were all foam!

 

[petrolSpice]

I think you have it backwards. The colder the temp, the less sugar it will tell you to use, for reasons mentioned above. If you use the cold crash temp (34F for example), you will be underpriming the bottles by up to 50%, severely reducing carbonation.

Use the highest temp that the beer achieved after fermentation completed.

 

[BitterSweetBrews]

I had and posted this same question today. The Northern Brewer Calculator specifically says the current temp of the beer. Beersmith just says temp. I have always wondered about this and looked around today before priming. I have always used conditioning temp until I saw the Northern Brewer site today. I bottled half a batch that had been cold crashing using this, but now think I should have added about 50% more sugar. We will see what happens. I did purge the top of the bottles with CO2 before capping, so maybe that will help a little. I wish I would have thought about it a little more. The beer is a Berlinerwiess that should be around 3.5. Thankfully, using the amount of priming sugar I used will give me around 2.9-3.0 which is still some decent carbonation, so I should be OK. The rest is kegged, so I can always carb it a little higher.

 

[petrolSpice]

I had and posted this same question today. The Northern Brewer Calculator specifically says the current temp of the beer.

Poor wording on their part, and/or the calculator was made before cold crashing was popular.