DHdriver

Recipes 

I know the general science behind it, yeast turns sugar into CO2 building up pressure and dissolving in the beer.
I'm wondering why this takes 2 weeks (leaving aside conditioning/aging)? It seems like 4oz of corn sugar should be fermented out within 24-48hrs.
Now what happens? As CO2 is created does it rise to the top, fill the head space and dissolve from the top down, or once there is some pressure does it absorb/dissolve as it's created? And what kind of pressure do we see in a bottle during this? 12PSI set in a keg seems to carbonate within a week.

So who knows the science?
Thanks

ThickHead

Recipes 

The yeast eat up the sugar fairly quickly. However, it takes a while for the pressure to fully push the CO2 into solution. Even if you force carbonate using a keg it takes two weeks for this to happen at 12psi. Additionally, you want to wait for the yeast to fully flocculate after they have done their work and cleaned up after themselves.

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Jayhem

Recipes 

^Pretty much covered it right there. It's not just carbonating, it's also "conditioning" which is when the small amount of yeast left in the bottle start breaking down their own waste byproducts and then settle out in a fine layer on the bottom leaving your beer fairly clear and smooth tasting. This process takes time!

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TheBiGZ

Recipes 

Also worth mentioning that CO2 is absorbed much faster if the beer is cold...as with force carbing.

WoodlandBrew

Recipes 

Nilo has an awesome blog post about this. He put a pressure gauge on a bottle and plotted the pressure over time.

http://beertech.blogspot.com/2009/12/carbonation-test.html

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AnOldUR

Recipes 

Lots of information in this thread. Especially the last half.

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DHdriver

Recipes 

That's much higher pressure then I would have expected