Adding more honey and calculating abv

[rockittear]

I started my first batch of mead about a week ago and fear I lost a lot of honey in the process (didn’t scrape up as much as I could’ve). I have a possible abv of about 9% and it’s a five gallon batch. I used Lalvin EC-118, which wasn’t my first choice, but I used it for its wide temperature range, and I know it can tolerate abv up to 18%. Is there a way I can add more honey to my batch and still calculate the gravity/abv? It seems like a waste to use EC-118 and end up with a low abv product, but it’d also be a real shame to blindly add more honey and not know my first mead’s abv. Any advice, suggestions, maybe complex formulas for calculating possible abv under these circumstances? Any input or information is appreciated

 

[VikeMan]

Sure, you need to calculate a new "effective original gravity" based on your original OG and volume, and the OG and volume of whatever you are adding:

(OG1 - 1) x (V1) + (OG2 - 1) x (V2)
----------------------------------------- + 1
(V1 + V2)

Then, take that effective OG along with a measured FG (after the addition ferments), and compute your ABV.

ETA: the above is a general formula. Mead experts probably have a shortcut for honey additions.

 

[bernardsmith]

My rule of thumb is that 1 lb of honey added to water to make 1 gallon of must will increase the gravity of the water by 35 points (1.035). If you are adding a pound of honey to a gallon of mead then I would assume that the added honey will increase the nominal density by a little less (the volume being more than a gallon) , so you might treat the addition as a nominal increase of about 25 -30 points (of course, if you remove the same volume of liquid as the mass of honey you are adding to make room for the honey then you can use the rule of thumb of 35 points). But this is a rule of thumb. You are not answerable to the IRS or TTB etc so accuracy to the fifth place after the decimal point is not the issue.

 

[videojunkie1208]

How did you lose the honey? Are you suggesting that it didn't get stirred up properly and is at the bottom of the jug? Or did it not wind up in the fermenter?

 

[rockittear]

Sure, you need to calculate a new "effective original gravity" based on your original OG and volume, and the OG and volume of whatever you are adding:

(OG1 - 1) x (V1) + (OG2 - 1) x (V2)
----------------------------------------- + 1
(V1 + V2)

Then, take that effective OG along with a measured FG (after the addition ferments), and compute your ABV.

ETA: the above is a general formula. Mead experts probably have a shortcut for honey additions.

This is exactly what I was looking for. Thanks!

 

[rockittear]

How did you lose the honey? Are you suggesting that it didn't get stirred up properly and is at the bottom of the jug? Or did it not wind up in the fermenter?

Didn’t wind up in the fermenter. I also think I used too much water. 12 lbs of honey equals a gallon so I’m thinking 12-15 lbs plus 4 gallons of water makes a 5 gallon must. I used 5 gallons of water so I have closer to 6 gallons

 

[bernardsmith]

Well, 12 lbs of honey in 6 gallons of must = 2 lbs per gallon which is about 1.070 and that has a potential ABV of about 9% . Fifteen pounds of honey in 6 gallons of must (and you would need to remove some of the current volume to maintain the same total volume after adding another 3 lbs of honey ) = 2.5 lbs honey / gallon = an SG of 1.085 which has a potential ABV of about 11.5%

 

[videojunkie1208]

Didn’t wind up in the fermenter. I also think I used too much water. 12 lbs of honey equals a gallon so I’m thinking 12-15 lbs plus 4 gallons of water makes a 5 gallon must. I used 5 gallons of water so I have closer to 6 gallons

Did you weigh your honey before you added it? Some 'gallons' of honey weigh more than 12 lbs.