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Old 04-28-2013, 02:50 AM   #1
JDFlow
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Default how's this possible...?

Pre-boil gravity 1.037

60 minute boil

Original gravity 1.04

How is that possible?

My pre-boil sample was 1.02 @ 153° according to the correction chart and calculator that brings it to 1.038. My OG sample was 1.038 @ 80° the same calculator and chart bring that to 1.04. I'm kinda pissed because that makes no sense.



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Old 04-28-2013, 02:55 AM   #2
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The accuracy of the correction charts goes WAAAAAYYYY down the further away from the calibration temperature you are.

If you really want to be accurate, you have to 1) cool the sample to the calibration temp or 2) use a refractometer



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Old 04-28-2013, 02:59 AM   #3
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+1
What I do is take the sample from the full boil volume, cool it, take the gravity reading, add the sample back to the boil.

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Old 04-28-2013, 03:48 AM   #4
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+1
What I do is take the sample from the full boil volume, cool it, take the gravity reading, add the sample back to the boil.
You're a genius! Doing this from now on.
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Old 04-28-2013, 03:53 AM   #5
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Originally Posted by Punx Clever View Post
The accuracy of the correction charts goes WAAAAAYYYY down the further away from the calibration temperature you are.

If you really want to be accurate, you have to 1) cool the sample to the calibration temp or 2) use a refractometer
I can see that, but my OG sample was only 10° off. Also, I just realized I filled my kettle to the 6.5 gallon mark, not the 6. I'm a dumbass...problem solved. Turns out my efficiency was 77% with the updated water calculation. Not bad. This was my first batch using mineral, salt, and acid, water additions too. I hope 1.04 doesn't taste super watered down.
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Old 04-29-2013, 03:13 AM   #6
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as far as original gravity and pre boil gravities go, can someone plz help me out. Just finished my first all grain brew today. Didn't run across a single problem (to my knowledge) with my newly built beer stand/ coolers/ pump/ etc. Bonus! Well, after mashing and fly sparging, the gravity in my brew kettle was 1.040 at approx 140 degrees. according to a piece of paper, it should be around 1.044-1.045 at 60 degrees where the hydrometer is calibrated too. Anyways, my post-boil gravity at 80 dgrees was 1.051, and being a total newbie to this, is that how its supposed to work?? It kind of makes sense to me that after 60 minutes of a rolling boil, the water level drops so the sugar content would be higher, but I just want to confirm that im not crazy, cuz if so, I hit my numbers perfectly according to the recipe, and brewersfriend.com calculations. It's saying my brewhouse eff. was 72%, which im totally happy with, being my first batch, on all this new equipment i recently built/ welded/ slaved over for the last few weeks. Anyways, just the assurance from someone more experienced confirming all this would help me sleep better tonight...even tho ill probably still go stare at the airlock another few times tonight, waiting for activity....thanks in advance, sorry to hijack a thread...i just thought it was kind of related.

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Old 04-29-2013, 03:21 AM   #7
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Originally Posted by silver01ram View Post
as far as original gravity and pre boil gravities go, can someone plz help me out. Just finished my first all grain brew today. Didn't run across a single problem (to my knowledge) with my newly built beer stand/ coolers/ pump/ etc. Bonus! Well, after mashing and fly sparging, the gravity in my brew kettle was 1.040 at approx 140 degrees. according to a piece of paper, it should be around 1.044-1.045 at 60 degrees where the hydrometer is calibrated too. Anyways, my post-boil gravity at 80 dgrees was 1.051, and being a total newbie to this, is that how its supposed to work?? It kind of makes sense to me that after 60 minutes of a rolling boil, the water level drops so the sugar content would be higher, but I just want to confirm that im not crazy, cuz if so, I hit my numbers perfectly according to the recipe, and brewersfriend.com calculations. It's saying my brewhouse eff. was 72%, which im totally happy with, being my first batch, on all this new equipment i recently built/ welded/ slaved over for the last few weeks. Anyways, just the assurance from someone more experienced confirming all this would help me sleep better tonight...even tho ill probably still go stare at the airlock another few times tonight, waiting for activity....thanks in advance, sorry to hijack a thread...i just thought it was kind of related.
It sounds like everything went very well and yes, your preboil gravity will be lower than your OG unless you do something very wrong. The sugars are much more concentrated after the boil.

I would not expect your numbers to be so spot on in the future. I have experienced a swing on my numbers. Sometimes better and sometimes worse. I don't fret about it too much since the beer is always very good.
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Old 04-29-2013, 03:32 AM   #8
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Originally Posted by kh54s10 View Post
It sounds like everything went very well and yes, your preboil gravity will be lower than your OG unless you do something very wrong. The sugars are much more concentrated after the boil.

I would not expect your numbers to be so spot on in the future. I have experienced a swing on my numbers. Sometimes better and sometimes worse. I don't fret about it too much since the beer is always very good.
Thanks for the quick reply, and confirming the higher gravities after boil. When thinking about it, it made sense, but I wasn't sure. And yeah, i totally expect my numbers to fluctuate, but being my first all grain batch, I was very happy to hit the numbers, and not end up with a totally messed up batch. One question tho, the original gravity is pre-boil or post boil??? The recipe says expected original gravity. 1.045...if that's preboil then i nailed it....if it after boil, pre-fermenter, then i guess im over that...sorry for noob questions...jumped head over heels into allgrain, and what a blast!!
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Old 04-29-2013, 05:23 AM   #9
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OG is post boil, what goes into the fermenter.

To add to your previous question, it's sometimes helpful to think of gravity in terms of total gravity points. As an example, two gallons at 1.050 is 50x2, 100 total gravity points. If you boiled the two gallons down to one gallon you'd have a gravity of 1.100, 100 total gravity points divided by one gallon. Same amount of sugar, but in a different volume. Being able to accurately determine volumes is important to the gravity calculation.



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