A refractometer is on my next toy list. 0-32 brix
This article is what tickled my fancy
Measuring Alcohol And Residual Solids
in Wine
by Werner Roesener
This is an easy method, yielding instantaneous results of the alcoholic strength as well as residual solids (sugar) in finished wine.
Equipment required:
1. A narrow range hydrometer (SG 980 - 1022), Note 1
2. A refractometer, calibrated for 0 - 32 Brix
The method is based on the scientific facts that the gravity of wine is affected by alcohol in one direction (lighter), and by sugar solids in the opposite direction (heavier). The refractometer, however measures the optical bending of light traversing through a wine sample, and both sugar and alcohol produce readings in the same direction (increased brix reading for both).
The procedure is to take a hydrometer reading, record the SG , then to place a small drop of wine on the refractometer prism and record the resulting brix reading. Those two numbers are then placed into the following formulae to obtain alcohol and solids content.
Alcohol (vol %) = (B * 4.16 - SG + 1000) * 0.365
Solids (g/L) = (SG - 1000 + ALC * 1.264) * 2.52
Where SG is in 3 or 4 digits, ALC is in vol %, B is the brix reading. To expedite the calculation, the formulae can be entered into a programmable calculator (Note 2), or into a PC program in BASIC, C or PASCAL. It should be kept in mind that solids are made up of mostly sugar, but also the acids and other minor solid components in wine. When dealing with sweet wines, pretty near all of the solids can be assumed to be sugar. The measurement accuracy is affected by temperature. It is essential that all involved items are stabilized at the same temperature, preferably in the 15 - 18 degree Celsius range. I have been asked if the method would be suitable for following the fermentation progress. In principle, yes, but the cloudiness of fermenting wine blurs the refractometer reading, making it difficult to obtain meaningful numbers.
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Here is a numerical example:
A port wine produces these readings: SG 1022, Brix 18.3
Calculation results: 19.8 % alcohol, 118 g/L solids
Edited by: scotty
