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Author Topic: Final Gravity question  (Read 3130 times)

Offline Waterlogged

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Final Gravity question
« on: May 10, 2013, 09:57:09 AM »
Hi, I have a finished gravity question.
I bottled my second partial grain last night.  It was the ZZ Todd Barley Wine from Noble Grape.  When I racked from the primary bucket into the carboy 2 weeks ago, I was sure the hydrometer read 1.020 FG.  So last night I calculated my priming sugar for the specified volume of CO2, boiled it in some water, added it to my bottling bucket and then racked the beer into the bucket.   I then took a final reading and was surprised to see the SG at 1.024.  This still gives me an ABV of 9.3% and I didnít think much of it until I was finished and started looking on the web regarding final gravities.  There I read about bottles blowing up.  I used grolsch bottle so I donít think they will pop the caps but should I still be worried about the beers foaming when opened?  I did see reference that the FG of most American and British Barley Wines were 1.024 Ė 1.03 so I am thinking I am good.  I plan on letting this mature for several months (possible until Christmas) but may have to open on in a few weeks to see how it is doing.  Any thoughts on the 1.024 final gravity?
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On Tap: Hoppy Porter
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Offline Chris Craig

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Re: Final Gravity question
« Reply #1 on: May 10, 2013, 10:20:24 AM »
There could be a couple of reasons for the reading changing like that, though 4 points is unlikely.  First, your priming solution wasn't mixed well into the beer, and you happened to take a sample that had more sugar.  Second, and more likely, your hydrometer was sticking to the side of the test jar.  Do you spin the hydrometer?  You should be spinning it before you take the reading, and I'd take 3 readings from the same sample to be sure.

As for bottle bombs, you're almost certainly safe, especially with Grolsch bottles.  There are a lot of things that will affect your FG.  Mash schedule, the yeast you use, the temperature you ferment at, and especially the quantity of yeast you pitch.

What yeast did you use, what was your OG, and what were you expecting the FG to be?

Offline Richard

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Re: Final Gravity question
« Reply #2 on: May 10, 2013, 10:58:04 AM »
1.024 for a barleywine is well within what I'd expect, although knowing your mashing schedule/yeast strain would help. I would also remind you that temperature drastically affects gravity readings - make sure you correct for temp.
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Offline Chris Craig

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Re: Final Gravity question
« Reply #3 on: May 10, 2013, 11:01:24 AM »
Good point Richard.  I used to use this site: http://www.brewersfriend.com/hydrometer-temp/

Offline McKraken

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Re: Final Gravity question
« Reply #4 on: May 10, 2013, 04:20:46 PM »
Just checking some math here. Correct me if I'm wrong, still new to this.

Assuming corn sugar has has a potential extract of 45 ppg (I have found conflicting info on potential extract for corn sugar, anywhere from 37-47ppg) and assuming a 5 gal batch size.

extract (in points)=(ppg*mass)/batch size in gal

points=(45*n)/5 gal

n=(4pt*5gal)/45

n=0.44444...lb  or 7.1...oz of corn sugar

It would take 7.1 oz corn sugar to bring up the gravity of a 5 gal batch by 4 points.  Typical priming sugar packets for kits would have between 4 and 5 oz corn sugar.

Basically, that's just showing my math backing up what CC already said.  The biggest variable is the potential extract, which could be figured out by taking a pound of dextrose and a gal of water (or a scaled experiment), and measuring gravity.
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Offline Waterlogged

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Re: Final Gravity question
« Reply #5 on: May 16, 2013, 11:15:56 PM »
Thanks for the comments. The beer was a partial grain kit from noble grape so the mash was only 20 minutes @ 155 and then a ton of extract added before the boil.   I also corrected for temp and that only made a 0.001 difference in the final gravity. I finally tried a bottle after two weeks priming and am very happy with the results. Nice and malty, spicy and glade I used I priming sugar calculator because it was, patting myself on the back, perfectly carbonated for my taste.  Will. Try to let it mature for a couple of month more and see what the end result will be. Ordering all the gear to do 15 gallon bIAB batches tomorrow. wish me luck.
Fermenting: Air
On Tap: Hoppy Porter
Bottled:  Air

Offline brew

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Re: Final Gravity question
« Reply #6 on: May 17, 2013, 09:15:47 AM »
Luck...

15g BIAB - nice...
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Offline chrismccull

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Re: Final Gravity question
« Reply #7 on: May 17, 2013, 09:31:57 AM »
Quote from: "Waterlogged"
Thanks for the comments. The beer was a partial grain kit from noble grape so the mash was only 20 minutes @ 155 and then a ton of extract added before the boil.   I also corrected for temp and that only made a 0.001 difference in the final gravity. I finally tried a bottle after two weeks priming and am very happy with the results. Nice and malty, spicy and glade I used I priming sugar calculator because it was, patting myself on the back, perfectly carbonated for my taste.  Will. Try to let it mature for a couple of month more and see what the end result will be. Ordering all the gear to do 15 gallon bIAB batches tomorrow. wish me luck.


Are you buying from these guys: http://www.biab-brewing.com/

Offline Waterlogged

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Re: Final Gravity question
« Reply #8 on: May 17, 2013, 09:37:49 AM »
No, I am getting everything from OBK. Should have it sometime next week. My first grain order is in on the bulk order but may have get some from noble grape since it probably won't be here for some time.
Fermenting: Air
On Tap: Hoppy Porter
Bottled:  Air