How to change abv after brewing

[CornoMusic]

I brewed an extract recipe which called for a longer boil than I normally do. I only had so much sanitized water to add and I have an OG of 1.060 in the primary. I anticipate a FG of 1.012 which will result in an abv of about 6.2%. If I want to get that abv down to 5.7% is there a calculation formula I can use to figure how much water to add; and can I do this water addition at bottling when I add my priming sugar?

 

[DaNewf]

Sorry I have no advice to give but can I ask why dropping it a half percent is important.

Feel free to to tell me MYOB but I'm curious.

 

[TyTanium]

I would wait to see where your FG finishes up first; it may not get down to 1.012.

 

[CornoMusic]

DaNewf,
That is a fine question. Normally I wouldn't worry with it, but I am going for a specific taste and I believe a higher abv will affect the taste. I'm thinking getting the abv down will help me with getting a slightly drier tasting ale.
Ty,
Good point. I don't mean to over react, it might not go all the way down to 1.012, or it could go further I suppose and obviously I will wait until fermentation is complete. If it stops at 1.013 then I've nothing to worry about and won't make any adjustments. I'm trying to be prepared for bottling day and would like to know how to adjust whatever FG I get, if I need to.

 

[fuzzy2133]

When you add water post fermentation you are also diluting the flavor.

 

[TyTanium]

Adjusting is just a matter of ratios:

(5 gallons x 6% alcohol) = (X gallons x 5.7% alcohol)

Solve for X...X = 5.26, so dilute by a quart. Rough approximation, but it'll get you close.

 

[Norselord]

Adjusting is just a matter of ratios:

(5 gallons x 6% alcohol) = (X gallons x 5.7% alcohol)

Solve for X...X = 5.26, so dilute by a quart. Rough approximation, but it'll get you close.

Not to be a "mierenneuker" but due to hydrogen bonding volumes of alcohol and water are not additive nor conservative. i.e. adding 50ml of water to 50ml of ethanol will not result in 100ml of solution.

Again that's just me being an "ant****er"

 

[CornoMusic]

Okay,
So in 5 gallons I have 640 oz at 6.3% which means I have 640 x .063 = 40.32 actual ounces of alcohol.
"X" x .060 = 40.32
"X" = 670. I need a total of 670 ounces of liquid. I presently have 640 ounces. so by adding 30 ounces (just barely less than a quart as Ty said) I can bring my abv down to 6%.

This is IF my terminal gravity is at 1.012. We will see and do math accordingly. Thanks all.

Norselord - I'm all for nitpicking. By exploring extreme truths we can then choose our level of compromise accordingly. So do you happen to know how I would account for the hydrogen bonding issues? Just for fun of course at this point.

 

[Norselord]

Okay,
So in 5 gallons I have 640 oz at 6.3% which means I have 640 x .063 = 40.32 actual ounces of alcohol.
"X" x .060 = 40.32
"X" = 670. I need a total of 670 ounces of liquid. I presently have 640 ounces. so by adding 30 ounces (just barely less than a quart as Ty said) I can bring my abv down to 6%.

This is IF my terminal gravity is at 1.012. We will see and do math accordingly. Thanks all.

Norselord - I'm all for nitpicking. By exploring extreme truths we can then choose our level of compromise accordingly. So do you happen to know how I would account for the hydrogen bonding issues? Just for fun of course at this point.

You need to do your addition on a mass basis, not volume. You don't have to 'account' for the hydrogen bonding.

 

[cheezydemon3]

Brew it different next time. Effing with a perfectly good beer is a BAD idea at best.

 

[feinbera]

While excessively-high ABV can make a beer "boozy," being off by half a percentage point does not qualify as excessively-high. If you were looking to come in at 8% or 9% on a beer that should've been 5.7%, you've got something to worry about, but the beer you've got would probably be indistinguishable from the beer you were trying for in a blind tasting.

To put it another way: the easy corrective measure is to add one little quart of water to five gallons of beer. Scaling down, that'd be about half an ounce of water in every 12-ounce bottle. If I got two identical bottles of beer, added half an ounce of water to one of 'em, and had you do a blind tasting, would you be able to tell the difference?

 

[techbrewie]

would someone explain how hydrogen bonding affects volume? If you add water to a finished beer, the volume changes by a linear amount and the amount of alcohol does not change at all. therefor the change in abv % should be linear as well. no chemical reactions occur either. It is my understanding that hydrogen bonding only happens under conditions of extreme temperature.

As for the OP, there are too many variables that change if you add water. the easiest route is to brew it again and changing your method. Although i very seriously doubt that .5% is going to be a noticeable variance in flavor.

 

[fuzzy2133]

Brew it different next time. Effing with a perfectly good beer is a BAD idea at best.

I agree.

I want to be better than AB/Inbev.

 

[Norselord]

would someone explain how hydrogen bonding affects volume? If you add water to a finished beer, the volume changes by a linear amount and the amount of alcohol does not change at all. therefor the change in abv % should be linear as well. no chemical reactions occur either. It is my understanding that hydrogen bonding only happens under conditions of extreme temperature.

As for the OP, there are too many variables that change if you add water. the easiest route is to brew it again and changing your method. Although i very seriously doubt that .5% is going to be a noticeable variance in flavor.

First google mierenneuken. I said right up front that is what I was doing.

In physics, mass is conserved, but volume is not. The hydrogens in water and alcohol like to be close to each other, and when a measured volume of water is added to a measured volume of alcohol the final volume is less than the two volumes together (50ml H2O + 50ml etOH = 95ml of 50% (by weight) solution) it is like the solution hugs itself and contracts. The total weight of the solution is the same as the components prior to adding.

Volume is not conserved. The difference in brewing is relatively insignificant, which is why you should google mierenneuken if you still haven't. But if you are designing a chemical plant where polar solvents and solutions are used it is a good idea to do all your material balances on a MASS basis, not a volumetric basis.

 

[CornoMusic]

Good point and excellent description Feinbera, and techbrewie. I suppose less than an ounce for every 20 oz bottle is not going to be noticeable. Certainly not by me. So I won't risk doing anything differently after all. And next time I'll just start with a larger beginning amount of water.

 

[passedpawn]

Not to be a "mierenneuker" but due to hydrogen bonding volumes of alcohol and water are not additive nor conservative. i.e. adding 50ml of water to 50ml of ethanol will not result in 100ml of solution.

Again that's just me being an "ant****er"

I've never heard that first term. The second one (that was caught by the profanity filter) I know. The english term is pedant, FYI. I am that myself sometimes (like right now).

I'd like to know what the resulting volume of that mixture is, if not 100ml.

 

[Hello]

Good point and excellent description Feinbera, and techbrewie. I suppose less than an ounce for every 20 oz bottle is not going to be noticeable. Certainly not by me. So I won't risk doing anything differently after all. And next time I'll just start with a larger beginning amount of water.

You mentioned drier beer. If this is definitely your goal be sure to brew it in such a way that it will be drier. Using sugar, for example, will help and then of course the yeast. Use a high attenuating yeast as 1.012 is not going to give you a very dry beer. Beers below 1.010 to me start to get dry. Using simple table sugar helps because it ferments fully and does dry out the beer. Also, adjust the mash temp.

Like everyone, most everyone, is saying here, don't bother with it or you could botch it. that 1/2 percent is not going to cause the beer to be boozy.

 

[boydster]

I'd like to know what the resulting volume of that mixture is, if not 100ml.

95ml

 

[KeninMN]

Here is the info you're looking for:

https://byo.com/stories/item/237-blending-for-volume-techniques

 

[passedpawn]

95ml

woops. thanks.