Original Gravity

[dhelegda]

Do you measure original gravity before or after the boil?


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[ChelisHubby]

it is after the boil has cooled down. But why would you consider before the boil, What would you try to measure.

 

[worlddivides]

it is after the boil has cooled down. But why would you consider before the boil, What would you try to measure.

Hm... 1.000... No fermentables... I wonder why... Oh, I haven't added them yet!

I've always measured after I've put the cooled-down wort in the fermenter and there is nothing left to add.

 

[thrack]

Hm... 1.000... No fermentables... I wonder why... Oh, I haven't added them yet!

I've always measured after I've put the cooled-down wort in the fermenter and there is nothing left to add.

I am sure he meant after the mash but before the boil.

 

[dhelegda]

Yes I just mashed. And am boiling now..thank you for noticing what I was talking about thrack! I always thought it was after boil...but John Palmers Book says for efficiency take gravity pre-boil.


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[betarhoalphadelta]

Yes I just mashed. And am boiling now..thank you for noticing what I was talking about thrack! I always thought it was after boil...but John Palmers Book says for efficiency take gravity pre-boil.


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Exactly. If you're trying to determine mash efficiency, you take a pre-boil specific gravity measurement.

After boiling, you then take another specific gravity measurement. Only the post-boil gravity reading is your "original gravity"...

 

[ChelisHubby]

Sorry but I am still doing extract with a little bit of crystals and what not. It didn't occur to me to check the mash.

 

[dhelegda]

Ok so I am bring a Belgian ale the OG is supposed to be 1.042 - 1.046 at my post mash pre boil I had a reading of 1.051. After boiling I should be at recommended gravity? I never take gravity always have had good beer so I am now trying to see if I can make great beer


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[Teromous]

When you boil off water your gravity will increase. To decrease gravity you can dilute it with water. If your pre-boil gravity is 1.051 it will be larger when the boil is finished. If you measure the amount of water that is evaporated during your boil, you can figure out what the gravity will roughly be when you are finished. This is a large reason why people take a gravity reading after running off their mash into the brew kettle. If you have lower than expected efficiency you can add extract, and if you have greater than expected efficiency you can add water. An important thing to note is that the temperature will be very high when running off your wort, which will throw off your hydrometer reading. You can wait for it to cool or calculate the gravity based on the temperature. Another thing you can do is buy a refractometer which will negate the need to use a hydrometer pre-fermentation.

 

[dhelegda]

I just got a refractometer for measuring OG. Hydrometer for FG


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[Yooper]

I just got a refractometer for measuring OG. Hydrometer for FG


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Did you calibrate your refractometer? Plain (distilled) water should read 0. Then, you can calibrate your refractomer to your hydrometer for the "wort correction factor". That way, you know your OG is correct. I hope that makes sense! Beersmith has a wort correction factor tool in it, but I know other software does too.

Take a preboil gravity and make sure you know your volume. That will give you your mash/lautering efficiency. Then, post boil, take another reading and note the volume, and that is your brewhouse efficiency.

 

[cjgenever]

Og is post boil. Starting gravity is pre boil. Fg is post fermentation. All are important.