Author Topic: Measuring Wort OG  (Read 956 times)

Offline flbrewer

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Measuring Wort OG
« on: January 11, 2015, 06:09:52 PM »
When would I check OG for my wort? I'm assuming once it's it the kettle. Anytime before that during the mash process?

Secondly, if I'm low at this point how much DME would I add to start raising points per gallon?

Offline Stevie

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Measuring Wort OG
« Reply #1 on: January 11, 2015, 06:22:36 PM »
There are two primary spots to measure the gravity. First is after you collected all of your wort and it has blended sufficiently. This is your pre-boil and will tell you how much sugar you got out of the grains.

The pre-boil is also where you would want to determine how much DME to add. Determine your gravity and subtract that from your expected. DME is about 40ppg. If you have 8 gallons of pre-boil volume, and your are 5 points short, you can add 1lb of DME to get you back up there.

Second is after the boil. This is no different from extract brewing.

There are other spots to measure, before lautering, mid boil, while sparging. I don't do any of those, but plenty of others do.
« Last Edit: January 11, 2015, 06:26:53 PM by Steve in TX »

Offline klickitat jim

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Re: Measuring Wort OG
« Reply #2 on: January 11, 2015, 06:50:20 PM »
Unless you are trying to duplicate a beer, which is very difficult to do on our scale and without blending worts and having a spot on taster, the most important gravity sample is post boil. If you are concerned about precise hop utilization then preboil is a good idea. The trouble is getting your first and second runnings thoroughly mixed so you aren't reading too low or too high. Some say it needs to be at a boil for that, then chill a sample and dilute or strengthen as needed. A gravity check of first runnings can give you an idea as to your conversion and extraction. Kai has a great chart for that, Gravity expected per quarts per pound.  If I am using a new to me grist I will draw a small sample and do a refractometer reading just to be sure.

Usually all I do is a post boil reading and a couple final gravity readings.

Offline HoosierBrew

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Re: Measuring Wort OG
« Reply #3 on: January 11, 2015, 08:47:33 PM »
I take a refractometer reading a couple minutes into the boil. The boil has the mixed pretty thoroughly by then, and especially on big beers, it tells me if I need to adjust with a little DME. Never need to on normal strength beers, though.
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Offline flbrewer

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Re: Measuring Wort OG
« Reply #4 on: January 12, 2015, 02:58:48 AM »
I just assumed reading pre boil is preferred so you can mix DME if needed and recheck all while dealing w non boiling wort. 

Offline reverseapachemaster

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Re: Measuring Wort OG
« Reply #5 on: January 12, 2015, 04:43:27 PM »
I usually check first runnings and then pre-boil, preferably right before I add the hops. There is a lot of currents in the wort mixing it up so it's the most accurate reading IMO. Then I check post-boil, post-cooling but pre-oxygenation. That is your OG reading.
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Offline denny

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Re: Measuring Wort OG
« Reply #6 on: January 12, 2015, 05:10:23 PM »
I just assumed reading pre boil is preferred so you can mix DME if needed and recheck all while dealing w non boiling wort.

FWIW, you're referring to specific gravity, which is a bit different.  OG refers to original gravity, the gravity as which the beer starts fermenting.  FG refers to final gravity, the gravity when it's done fermenting.  Any other time, you're measuring SG or specific gravity.
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Offline flbrewer

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Re: Measuring Wort OG
« Reply #7 on: January 12, 2015, 05:12:14 PM »
^^oh! Thanks.