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Old 06-03-2010, 02:33 PM   #1
FenoMeno
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Default refractometer readings

Will the refractometer read correctly after fermentation? I recently purchased one, and used it on my last brew. Instructions were not very clear--

Am I correct that it can be used pre/post boil, but use my hydrometer to check SG during fermentation?

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Old 06-03-2010, 02:41 PM   #2
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Quote:
Originally Posted by FenoMeno View Post
Will the refractometer read correctly after fermentation?
No, alcohol has a higher refractive index than water and a lower density.

So a finished beer might have a refract reading of about 6 (equivalent to 1.024),
but a hydrometer reading of 1.012.

There are calculators available in Beersmith and online to estimate the FG of a beer based on the OG and the final refract reading.
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Old 06-03-2010, 02:49 PM   #3
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Simple correction:

Formula for compensation of ethanol effect on refractometer:

SG=1.001843-0.002318474(OB)-0.000007775(OB^2)-0.000000034(OB^3)+0.00574(AB) +0.00003344(AB^2)+0.000000086(AB^3)

SG = Specific Gravity, OB = Original Brix, AB = Actual Brix (Brix Readings During Fermentation)

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Old 06-03-2010, 03:17 PM   #4
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Thanks,
I have BeerSmith, never noticed the Tab to select what "stage" I am measuring. (defaults to Unfermented Wort Gravity)

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