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All New Newbee Guide to making Mead

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epetkus

NewBee
Registered Member
Jan 1, 2009
378
2
0
Florida
First of all, THANK YOU for having this and updating it for all of us!!!!! What a tremendous resource for the Mead community!

Second, in looking at the ABV/Brix/SG charts, there is either a significant error in the table, or I don't understand how to read it!

Specific example: The table shows an SG of 1.010 equates to a Brix of 3.8. This is wrong. An SG of 1.01 = ~2.56 Brix (born out by both my Hydrometer and the formula B=261.3*(1-1/SG)).

Is the column heading wrong, or the formula, or am I missing something?

ERic
 

JamesP

Senior Member
Lifetime GotMead Patron
Dec 3, 2003
654
1
0
53
Brisbane Australia
If you are fermenting to SG=1.00 like your hydrometer is calibrated to (zeros at SG=1.000), then 2.56 is probably correct.

The 3.8 assumes you are actually going lower (or has the potential to go lower to say 0.995 ), and that the extra sugars are still in solution at SG=1.000

Note, adding an amount of honey to water to get sg=1.010 will be different to fermenting from sg=1.125 down to sg=1.010 because the alcohol in the mead affects the SG
 

JamesP

Senior Member
Lifetime GotMead Patron
Dec 3, 2003
654
1
0
53
Brisbane Australia
If you are fermenting to SG=1.00 like your hydrometer is calibrated to (zeros at SG=1.000), then 2.56 is probably correct.

The 3.8 assumes you are actually going lower (or has the potential to go lower to say 0.995 ), and that the extra sugars are still in solution at SG=1.000

Note, adding an amount of honey to water to get sg=1.010 will be different to fermenting from sg=1.125 down to sg=1.010 because the alcohol in the mead affects the SG
 

epetkus

NewBee
Registered Member
Jan 1, 2009
378
2
0
Florida
If you are fermenting to SG=1.00 like your hydrometer is calibrated to (zeros at SG=1.000), then 2.56 is probably correct.

The 3.8 assumes you are actually going lower (or has the potential to go lower to say 0.995 ), and that the extra sugars are still in solution at SG=1.000

Note, adding an amount of honey to water to get sg=1.010 will be different to fermenting from sg=1.125 down to sg=1.010 because the alcohol in the mead affects the SG
JamesP, not sure I quite understand your comment. It seems to me that the calculation of SG to Brix (or vice-versa) is independant of the method at which you arrived at your solution to be measured (sugar/honey to water or conversion of sugars to alcohol due to fermentation).

All I'm trying to point out is that there is a discrepency between this table and other resources:

http://www.fermsoft.com/gravbrix.php
http://www.brewheads.com/brixsg.php
The Brix formula at the bottom of: http://www.valleyvintner.com/Refrac_Hydro/Experiment.pdf
The 1942 widely used reference document: http://www.boulder.nist.gov/div838/SelectedPubs/Circular 440 Table 114.pdf

Etc., etc.

I've found this same table here: http://www.brsquared.org/wine/CalcInfo/HydSugAl.htm where the focus is on calculating percent alcohol (PA).

So, how do we clear this up?

Eric
 

akueck

Certified Mead Mentor
Certified Mead Mentor
Jun 26, 2006
4,958
10
0
Ithaca, NY
I think the discrepancy is between a sugar-water solution and a sugar-water-alcohol solution. Brix is % sugar, which is not the same as SG--which is just density--but there are ways to calculate one from the other. In a sugar-water solution, the correlation between Brix and SG is different than it would be for a sugar-water-alcohol solution, as alcohol and water have different densities. (James' comment assumes an alcohol-water density of 0.995 for example.) When there is alcohol in the mix, a SG of 1.000 corresponds to a nonzero amount of remaining sugars. For just sugar-water, 1.000 means no sugar. The difference isn't earth-shattering but could easily account for about 0.005 SG or 1ish Brix.
 

Medsen Fey

Fuselier since 2007
Premium Patron
Eric, thanks for posting the link to the National Standards Board (1942). I like going straight to the source. ;)

I think that answers the question nicely - for a sugar water solution, the Brix 2.56 is equivalent to a gravity of 1.010.

As Aaron points out, the BRsquared chart is designed to try to help calculate alcohol content in a wine or mead and I think it is taking into account the fact that the actual sugar concentration is higher than what the refractometer reads because the alcohol (with a gravity of 0.7851) is making the reading lower. That is why a mead really isn't dry at 1.000, but actually needs to get down close to 0.990 to be completely dry. A lot of calculators make this kind of correction with their formulas when calculating for a ABV.
 

epetkus

NewBee
Registered Member
Jan 1, 2009
378
2
0
Florida
Excellent!

Thanks Aaron & Medsen & JamesP for clearing this up with regards to the table. Of course, now I'm wondering why my supposed wine hydrometer is calibrated to water!

In any case, it seems that an "adjustment" of ~-0.005 SG needs to be made to the FG reading (in SG on the hydrometer) to account for the alcohol in the mixture lowering the reference point.

For example, using my last batch, I had an OG = 1.131 SG/30.5 Brix as measured on my (water referenced) hydrometer (which is accurate since it truly is a water-sugar mixture at this stage).

I had a Final SG of 1.010 resulting in an equivalent ABV SG value of 1.121 or ~16.2% ABV. However, reducing this final number by 0.005 yields an equivalent ABV SG number of 1.116, or 15.5% ABV.

If I used the Brix scale on the same hydrometer, OG=30.5 Brix and FG = 2.5 Brix, that results in an equivalent ABV Brix value of 28 or ~15.5% AB.

So, back to the newbee guide, it may be worth having both a sugar-water conversion along with the sugar/water/alcohol conversions. Obviously, our pre-fermented musts are the sugar/water type, so anyone wanting to convert SG-to-Brix at that stage would be better served with the water-referenced table.

Thanks again all!

Eric
 

Medsen Fey

Fuselier since 2007
Premium Patron
Yes you get different answers depending on which formula you use. The simple 131*gravity drop says 15.8%, and I find that is usually close, but you can easily be off by 0.5%, and then when you factor in different amounts of evaporation of alcohol depending on temperature and such, calculating alcohol based on gravity changes can be +/- 1%.

If you measure alcohol by spirit indication you can get a more precise answer. I also think the hydrometer + refractometer calculations give a more precise answer because you are directly measuring the alcohol impact.


P.S. Does anyone think the guide needs a section on stabilizing and backsweetening?
 

Angus

Lifetime Patron
Lifetime GotMead Patron
Aug 19, 2005
908
0
0
51
Milwaukee, WI
Good suggestion on the stabalizing and backsweetening. I will write up another chapter and insert it ASAP.

Also, I think I will do a little more description on the Brix/SG issue. I asm trying to keep it as simple as possible though as it is a NewBee guide, but the issue clearly warrants some form of clarification.

Thanks guys. By the way, the screen-shots from the Calculator seem to be a little garbled. Can you guys read them properly?

Angus
 
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