80% fill for better carbonation?

In my last 3-4 batches I have had one last bottle only filled about 80% full. On all accounts, this bottle has been the best/most carbonated, retaining the best head and having the most bubbles throughout the glass as I drink it.

Might it be a good idea to fill all of my bottles to about 80-85% instead of all the way up to get better carbonation? I've never had one explode or even a geyser/gusher.

I use 22oz glass bottles with regular crown caps.

Thanks!

I can't say that my partially filled bottles are carbonated better than full bottles, but they certainly carbonate just fine. I have had no problems with partially filled bottles carbonating.

MaltMonster said:

I can't say that my partially filled bottles are carbonated better than full bottles, but they certainly carbonate just fine. I have had no problems with partially filled bottles carbonating.

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My partial fills (all 75-85%) are certainly carb'd better. I'm sure there's a scientific explanation behind it, but I haven't had enough to drink tonight to make that explanation up!

I'll have to start paying better attention.

If I recall correctly, under filled bottles will carbonate more, while over filled bottles will carbonate less. You might want to adjust the amount of priming sugar you use to get a bit more carbonation in the regularly filled bottles. Or figure out the temperature of the wort for the calculation tools so that you get more accurate sugar amounts to use for priming.

How long are you letting the normal fill bottles sit? Assuming you have them at close to 70F (or in that area for most of the day)...

They sit at about 66F for most of the day, but the ambient air temp gets up to about 72F from 5pm to 10pm daily. I let everything sit in this environment for 4 weeks before cracking the first bottle. Perhaps I'll start filling just a tinge less.

I had been using a 1/2 inch filler and carbonation when down. It makes sense because more head space got CO2 that beer didn't. I ended up topping them off after I figured it out. Now I use the regular 3/8 filler. Lack of head space is why it takes less to prime a keg.

Bottling from a keg the head space has even more impact. CO2 will come out of the beer into the head space. I try to not leave much.

i always thought you would get bottlebombs if they were underfilled.maybe i am wrong. i usually have one and a half to two inches of headspace in the neck

Man, doesn't make any sense to me that under filling would lead to more carbonation in the beer. Would think it would be the opposite, since more vapor space would mean lower pressure and therefore lower equilibrium concentration of co2 in the beer. Not questioning what anyone has experienced, just seems opposite of what I would expect.

discnjh said:

Man, doesn't make any sense to me that under filling would lead to more carbonation in the beer. Would think it would be the opposite, since more vapor space would mean lower pressure and therefore lower equilibrium concentration of co2 in the beer. Not questioning what anyone has experienced, just seems opposite of what I would expect.

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Isn't dat veird? It does seem contrary to logic,but answer seems to be that the greater head space leaves more room for gas to collect. Then disperse into the bear once a certain pressure is reached that's needed to make that happen. Then,when you pop'em in the fridge,it's like a cold crash. The sediment compacts more,& CO2 is forced into solution. The result? more carbonation,more/better head.
More time in the bottle conditioning also seems to make more carbonation,besides better color/flavor.