Re: Balling Scale Readings

Sep 23, 2003 1 Replies

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Crushed 900 lbs of Cab and 900 lbs of Zin yesterday and took readings

> using a Balling Scale calibrated to 60 Deg F. The temp was 73 Deg F and
> the readings were 23.5 for the Cab and 22 for the Zin. Need a little
> help on the conversions to determine potential alcohol.

At 73ºF, you would ADD .001 to the specific gravity. That is equivalent to .25 degrees Brix (according to one formula). There are at least 28 formula for computing PA from Brix, and they are all rough approximations. Some of the variables are must temperature, solids

-other than sugar-- in the must, and the angle of lunar deflection. Formulas which come within 1% of the final alcohol (measured with an ebuliometer) are considered extremely accurate.

Using the scale on my triple-scale hydrometer:

1) Cab: Brix = 23.5 + .25 = 23.75 ~= 12.5 % p.a.
2) Zin: Brix = 22.0 + .25 = 22.25 ~= 12.0 % p.a.

This is the chart that came with my hydrometers (6 different brands, same chart):

Celcius Fahren Correction (to specific gravity)

10.0º C 50º F Subtract ½ 15.6º C 60º F ---none--- 21.1º C 70º F Add .001 25.0º C 77º F Add .002 28.9º C 84º F Add .003 32.2º C 90º F Add .004 35.0º C 95º F Add .005 37.8º C 100º F Add .006 40.6º C 105º F Add .007

Since one degree Brix ~= .22 SG thousandth, I determined .25 to be the Brix correction for 73ºF.

However .55 is NOT the correct factor for computing PA at 73ºF. That would be .59, but using the lower figure is will partially compensate for non-sugar components affecting SG. The Davis formula reduces Brix by 1.6º before using the temperature-based conversion factor. The difference is less than the known error in the formulae.

Re: Balling Scale Readings

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