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Old 11-27-2010, 02:17 AM   #1
pearlbeer
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Feb 2009
Austin
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I just got a cool refractometer. It has ATC. In fact, it is this model:
http://www.austinhomebrew.com/produc...ducts_id=12574

I calibrated it.

My Porter's OG (Measured via hydometer) read 1.059 (14.5 Brix)

Just checked the FG with the new tool and measured 1.025 (6 Brix)

Using several online calculators, that is an adjust FG of like 1.003, which seems awfully dry. It doesn't taste that dry and I mashed at 153.

Need to double with my hydrometer..but am I doing something wrong in reading this thing?

 
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Old 11-27-2010, 03:53 AM   #2
Paddle_Head
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I don't have much to offer other than I had the same thing happen. When I checked with my hydrometer later it was at 1.012. Not sure if its the ETOH or the nature of the remaining sugars.

 
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Old 11-27-2010, 04:06 AM   #3
passedpawn
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You cannot measure the gravity with a refractometer once there is alcohol. After adding yeast, you will need to rely on hydrometers.

Beersmith has correction tools that claim to allow you to do this, but believe me the resulting reading is not accurate. BYO magazine published all the formula to do this also, same result.

Sorry to be the bearer of bad news. I tried to make mine work for a long time, but I gave up (except for the pre-alcohol measurements).
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Old 11-27-2010, 04:27 AM   #4
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Agreed. They are not accurate with alcohol present; however, they seem to be fairly good until you get near FG at which point they tend to be anywhere from correct to about 5 points low. I find you can use the refractometer to see when you are "close". As soon as it says you are at your expected FG, chances are you are within about 5 points or so and at that point, you switch over to your hydrometer and check. If you like to check gravity a lot and don't use a thief (and in that case, possibly dumping your test jar each time), it is a good way to save beer.
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Old 11-27-2010, 02:02 PM   #5
logdrum
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What about this spreadsheet?

http://morebeer.com/learn_vids/vids_refract

 
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Old 11-27-2010, 04:45 PM   #6
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Quote:
Originally Posted by logdrum View Post
What about this spreadsheet?

http://morebeer.com/learn_vids/vids_refract
As far as I'm concerned, all the current methods/math of using a refractometer to measure fermenting beer are flawed.

This guy is on the right track to making it work, though. I'm waiting for the fallout from his data analysis before I continue doing this. Great work sean!

http://seanterrill.com/2010/06/11/re...final-gravity/
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Old 11-28-2010, 03:16 AM   #7
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Quote:
Originally Posted by passedpawn View Post
As far as I'm concerned, all the current methods/math of using a refractometer to measure fermenting beer are flawed.

This guy is on the right track to making it work, though. I'm waiting for the fallout from his data analysis before I continue doing this. Great work sean!

http://seanterrill.com/2010/06/11/re...final-gravity/
I have seen his site as well. Problem is that he has been trying to do this with very limited data which is making his current result flawed. What he should be doing is a) take more readings per batch so that he has more data points from the same OG and can track the data curve, and b) ask others to contribute data. I hope he continues the work as well, but by posting his current results, I am wondering if that is in his plans.
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Old 11-28-2010, 06:22 AM   #8
GC89
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In my experience the morebeer spread sheet is pretty accurate, I have used it for several batches and they have all been within 2 points or so as far as I can tell. I still use a hydro for FG but its great for monitoring fermentation.
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