Volume Semantics

[CityEggs]

Hello Got Mead. Been making Mead half of a year now and things are going great. A question dawned on me though that I think you all can help out with. Forgive me if this is simple, I couldn't figure out how to search for this specific answer:

I've made my own predictive gravity counter. So far it's pretty accurate, but I've only been doing 1 gallon batches. I'm making a 6 gallon batches now and the question came up as followed: I calculated 4 gallons of water with 15lbs of honey as 1.129 of, with a pABV of 19%. But someone said, no, it's really 15lbs of honey in 5 gallons to give you 16%. Figuring that 15lbs would as gallon of volume:

My hydrometer had shown me that my predictive readings were correct; but which is it? Honey to water or honey to total volume?


Thanks

 

[darigoni]

Have you look at the gotmead batch calculator? The link is at the top of this page.

You'll see that when talking batches, it's usually the overall volume: i.e. A 5 gallon batch with 15 pounds of honey. Which has an OG=1.108 and a potential ABV of 14.1%.

 

[CityEggs]

Thanks. I guess with small batches this is less of a problem. I will update my calculator accordingly, and go buy more honey

 

[Squatchy]

You might also care to know if you add a pound of honey to a gallon of water you will have 35 points of gravity.

 

[darigoni]

You might also care to know if you add a pound of honey to a gallon of water you will have 35 points of gravity.

Actually, if you add a pound of honey to one gallon of water, you will have a total volume of 1.0833 gallons and an SG=1.032.

What you mean is if you have a total volume of 1 gallon, which contains 1 pound (0.0833 gallons) of honey, you will have an SG=1.035.

 

[bernardsmith]

Yes... Adding honey to a gallon of water is NOT the same as adding honey to water to make a gallon

 

[Squatchy]

OK. You guys are correct no doubt. It's easy math to do what I said and the difference (at least in my mind) was not big enough to sweat the difference you have pointed out. But thank you for correcting me

 

[CityEggs]

Thank you for your replies. I have updated my calculator to use the total volume and weight of the must, and not just that of the water. Now as I play with it I can see that, adding 5lbs of honey to 4 gallons of water would result in a 1.04 gravity (which I recorded when I measured), but as each additional 5lb honey was added, it did not add a static 1.04; the second only added 1.03; and the third adding a little less; because each subsequent addition was being added to a larger volume. This makes sense for me as my original thinking was "well if each 5lb thing of honey adds 1.04. then I only need 3 to get to 1.2" when in reality I need 1 more 5lbs honey addition to get me there!

 

[rodlonq]

CityEggs, It is the law of diminishing return. You can add as much honey as you like to make up 5 gallons, the SG will never increase pat that of 100% honey (1.42 I think). The first lb makes the most effect and after that the effect reduces. The last pound would make very little to the SG. On the other hand, you can add 100 gallons of honey to 5 gallons of water and it will still be lower SG than pure honey. I have struggled with this component of recipes since I started reading, but the only way that makes sense is reference to total volume.