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Old 01-08-2011, 01:34 PM   #1
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Default When using the Beersmith or Promash refractometer tool is OG after boil or pre-boil

When entering the information into the refractometer tools is the OG number supposed to be from wort pre-boil or after boil?

If I enter the pre-boil gravity reading I took with my hydrometer of 1.049 and my first fermenting refractometer reading of 9.23 brix, the results line up with the fermenting hydrometer reading I took at the same time. >1.028<. But if I enter the post boil reading I took with my hydrometer of 1.062 the results in the refractometer tools are different. >1.021< That would mean my hydrometer reading during fermentation is wrong.

Which OG number should I use and what would cause my hydrometer to read incorrectly? Maybe CO2 floating the hydrometer?

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Old 01-08-2011, 07:49 PM   #2
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I use promash and I think that it can be for either. There is an option for into kettle or into fermenter. At least that is what I think the options are...I'm at work now and can't double check my memory. I always do the into kettle so I know what my mash eff. is.

Did you temperature adjust your readings?

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Old 01-08-2011, 07:51 PM   #3
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After fermentation begins, the presence of alcohol in the beer skews the readings of a refractometer. You use a refractometer to measure pre-fermenation gravity, either preboil or post boil.

There are software programs to account for the presence of alcohol in a refractometer reading that can adjust for it if you enter the OG, I believe, but they are not that accurate.

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Old 01-08-2011, 08:37 PM   #4
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After fermentation begins, the presence of alcohol in the beer skews the readings of a refractometer. You use a refractometer to measure pre-fermenation gravity, either preboil or post boil.

There are software programs to account for the presence of alcohol in a refractometer reading that can adjust for it if you enter the OG, I believe, but they are not that accurate.
I understand that the reading could be perfectly wrong but I think it's pretty close because when I enter the pre-boil gravity reading I took with my hydrometer of 1.049 and my first "fermenting" refractometer reading of 9.23 brix, the results line up with the fermenting hydrometer reading I took at the same time. >1.028<. In other word the hydrometer and refractometer readings are the same. So then if the refractometer reading is skewed, the gravity is something else and it is skewing it to the exact gravity I get with the hydrometer. It's only when I enter my post boil/prefermenting gravity of 1.062, that I took using a hydrometer, into the refractrometer tool, that the gravity reading in the refractometer tool is different from my hydrometer reading.
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Old 01-08-2011, 08:43 PM   #5
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Originally Posted by jetmac View Post
I understand that the reading could be perfectly wrong but I think it's pretty close because when I enter the pre-boil gravity reading I took with my hydrometer of 1.049 and my first "fermenting" refractometer reading of 9.23 brix, the results line up with the fermenting hydrometer reading I took at the same time. >1.028<. In other word the hydrometer and refractometer readings are the same. So then if the refractometer reading is skewed, the gravity is something else and it is skewing it to the exact gravity I get with the hydrometer. It's only when I enter my post boil/prefermenting gravity of 1.062, that I took using a hydrometer, into the refractrometer tool, that the gravity reading in the refractometer tool is different from my hydrometer reading.
I don't understand what you're saying. The pre-fermentation refractometer reading and the OG reading from the hydrometer HAVE to match. That's how it's calibrated. There is a small adjustment factor (mine is 1.033) that you do in the "calibrate refractometer reading" in Beersmith that fixes all the readings for you from then on. After alcohol is in the solution, THEN it's when there are complicated formulas to adjust.

If the OG from the hydrometer and refractometer don't match, then it's either the calibration tool, the calibration of the hydrometer, or the calibration of the refractometer. Distilled water should be 0 with both the refractometer and hydrometer, so check that first!
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Old 01-08-2011, 09:25 PM   #6
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Originally Posted by Yooper View Post
I don't understand what you're saying. The pre-fermentation refractometer reading and the OG reading from the hydrometer HAVE to match. That's how it's calibrated. There is a small adjustment factor (mine is 1.033) that you do in the "calibrate refractometer reading" in Beersmith that fixes all the readings for you from then on. After alcohol is in the solution, THEN it's when there are complicated formulas to adjust.

If the OG from the hydrometer and refractometer don't match, then it's either the calibration tool, the calibration of the hydrometer, or the calibration of the refractometer. Distilled water should be 0 with both the refractometer and hydrometer, so check that first!
Maybe that's where things are skewed because I did not take a post-boil, pre-fermentation reading with the refractometer, just with the hydrometer.
Only during fermentation have I used the refractometer along with the hydrometer.
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Old 05-02-2011, 04:10 AM   #7
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here is a site that you can use to use adjust for the presence of alcohol in your final gravity reading for the refractometer:http://seanterrill.com/2011/04/07/re...er-fg-results/

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Old 05-02-2011, 03:45 PM   #8
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i didn't read the above responses (sorry... lol) but OG would always be post boil. beersmith does have a spot on the brew sheet for pre-boil gravity, but in terms of an actual OG that would be used to determine ABV, you'd always take that reading post boil (and if doing a partial boil, after you've added your post-boil water and mixed well).

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