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Old 12-29-2010, 09:37 PM   #1
buckeyebrewer
 
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I got a new refractometer for Christmas. See Ebay ad below.....

http://cgi.ebay.com/0-32-Brix-Wort-S...62391629418637

I calibrated it right out of the box with purified water. It was exactly 1.000 when I put the water on it so there was no calibration needed. In the directions it said that it was calibrated at the factory as well so I didn't actually need to change the settings when I calibrated it. I had a beer that was done fermenting that I was racking to a keg. I took a reading and it said 1.024.....the sample was 66 degrees F and the refractometer has Auto Temperature Calibration from 10C - 30C degrees.
So I got my trusty old hydrometer out and took another reading. The hydrometer read 1.008. I drank the hydrometer sample and it tasted like it was 1.008....very little residual sugars left in the sample. I'm really confused how it could be so far off.....any ideas? Does the alcohol mess with the reading in some way? Thanks for any suggestions.
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Old 12-29-2010, 09:46 PM   #2
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Refractometers are dependent on their own readings. In other words, you have to take a refractometer reading of your wort pre-fermentation, and then another post-ferm. Then you can figure it out from there.

I have never been able to interchange readings from a hydrometer with readings from a refractometer...so I quit using my refractometer.

 
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Old 12-29-2010, 10:03 PM   #3
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I read the description on Ebay again and it says
"1.000 ~ 1.120 specific gravity scale for unfermented wort"
unfermented wort being the key phrase....does alcohol mess with the reading???
If so...why would anyone want one. I guess it would be handy during the boil to see where you were at....
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Old 12-29-2010, 10:10 PM   #4
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Yes, alcohol does interfere with the readings. There are procedures for compensating, but in my experience, none of them is very accurate (although I haven't checked them all). You also need to apply a Brix Correction Factor to your pre-fermentation readings to account for the differences between wort and sugar solutions. Promash and Beersmith have instructions for this, but I don't know about any other brewing software.

-a.
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Old 12-29-2010, 10:19 PM   #5
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The one I bought has a specific gravity scale in it. The directions included with it don't explain everything. Sounds like a big PITA....looks like the hydrometer it much better.
So will the refractometer take an accurate original gravity reading of unfermented wort?
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Old 12-29-2010, 11:11 PM   #6
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The only way to really find out is to try it with refractometer, and hydrometer. That will give you an accurate answer. I know that mine gives me readings within one or two points of what the hydrometer shows, but I can read the refractometer much more easily. It also, doesn't roll off the counter and smash into hundreds of pieces, and it works really well for telling me how the sparge is progressing (which is the main reason I bought it).

-a.
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Old 12-29-2010, 11:36 PM   #7
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Quote:
Originally Posted by buckeyebrewer View Post
So will the refractometer take an accurate original gravity reading of unfermented wort?
Yes. that's the main purpose, pre-fermentation readings, especially pre-boil and post-boil readings so that you can quickly find your efficiency and also to avoid over sparging. the 3 drops you need for a refractometer cool almost instantly vs the several ounces you need for taking a hydro reading.

post fermentation I just drop my sanitized hydrometer in the bucket, take the reading and move on.
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Old 12-29-2010, 11:40 PM   #8
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Use the refractometer for spot checking during all grain brew sessions, pre ferment. Then go ahead and use a hydrometer before packaging so you can taste the sample anyway.
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Old 12-30-2010, 01:17 AM   #9
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I too bought a refracto off Ebay recently and I've used it for 3 or 4 batches so far. The first two I did hydro readings along with it and it was spot on. I found several web sites that help with finding gravity based on the pre-ferment reading vs post/ferment readings. Without making the adjustments, it will seem way off once fermentation has started.

Here's one you might check out.

P.S. I LOVE MY REFRACTOMETER!!!
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Old 12-30-2010, 02:07 AM   #10
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Thanks everyone...makes good sense now...
what would I do without you guys/gals...I think I might cry
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