Does force carbing = lower ABV than using priming sugar?

[freisste]

Precisely.

And if your yeast only attenuated 75% (apparent attenuation), your 1.088 OG priming solution will ferment to 1.022, which is roughly 8.8% ABV (check my math, I did that in my head). So if you add it to a 5% ABV beer, it would increase the ABV. Exactly as you showed via the rule of mixtures. However, if you added it to a 10% ABV beer, it would reduce the ABV.

 

[Wallywombat]

Well in the interests of science & beer comradeship lets run your example 10% ABV homebrew and 20% priming solution
490 ml of 10% hombrew into our 500ml bottle adds 49ml of Ethanol. Adding 10 ml of 20% Glucose adds 2 grams of glucose which will ferment into 1.02 grams of Ethanol which is 1.29ml. Our bottle now has 500ml with 49+1.29 = 50.29ml = 10.06%ABV - a small increase indeed but 10ml of 20% Glucose will leave a pretty flat beer ( although possibly not in English pubs) and 10%ABV homebrew is near the top end.
At 7% ABV Homebrew and 10 ml of 50% Glucose solution the final ABV will be 7.51%, still significant I think. Especially when it comes to paying excise. Adding 5 grams of glucose powder to 500ml of 7%ABV will raise it to 7.65%ABV. Which is a having a sleep under a tree beer.
Regards from South Australia

 

[Wallywombat]

and adding either 20% or 50% priming solution will never lower the ABV. It will always increase it.Adding 300 ml of 20% priming solution to 200 ml of 7% ABV beer will give a final ABV of 10.6%.
Even starting with a 10% ABV beer and adding 10ml of 20% priming solution will give a final ABV of 10.06
Starting with 200ml of 10% ABV beer and adding 300 ml of 20% priming solution will give a 11.8% beer
Remember a 100 ml of 20% solution of glucose will become ( with perfect yeast ) 100ml of 12.96%ABV therefore you will only begin diluting your homebrew with priming if your homebrew starts with an ABV greater than 12.96%

 

[JustLooking]

From How to Brew:

Here's how to make and add priming solutions:
1. Boil 3/4 cup of corn sugar (4 oz by weight), or 2/3 cup of white sugar, or 1 and 1/4 cup dry malt extract in 2 cups of water and let it cool.......

This would give you a 1.088 solution and giving you the benefit of the doubt, at 90% attenuation, 10% abv. You can make your priming solution to a higher gravity and make the numbers say what ever you'd like, but that is not the standard most homebrewers go by.

 

[freisste]

Well in the interests of science & beer comradeship lets run your example...

And that is exactly how far I read before assuming you had me

So I'll respond with the following:

All I heard is that "priming with a solution with a lower OG than your beer's OG will result in a reduced ABV."

But seriously, thanks for showing the absurdity of my position. I still think we were both right from the start, although your position is much more practical.

 

[Wallywombat]

No I don't make the numbers say what ever I like. What I have shown is science.

 

[freisste]

No I don't make the numbers say what ever I like. What I have shown is science.

You lost me...

I never implied that is what you did. I never suggested you were twisting the figures. I never suggested you did anything wrong at all.

 

[Yooper]

For crying out loud. You bump a 4 year old thread to argue about nonsense?

I think all of us can find a better use for our time.