Author Topic: Measure post mash gravity vs Pre boil gravity  (Read 11073 times)

Offline andrew.grogan1

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Measure post mash gravity vs Pre boil gravity
« on: August 11, 2016, 08:19:39 AM »
What is the difference between "Measure post mash gravity and Pre boil gravity?  Should these numbers be the same?  Is it not just the gravity of wort before the boil?  They are 2 separate inputs. 


Offline Oginme

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #1 on: August 11, 2016, 08:36:10 AM »
Post mash is the gravity of the combined runnings from the wort collected from the mash.  Pre-boil gravity reflects the gravity of the wort from the mash PLUS any additions of extract or sugars made before the boil starts.
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Offline andrew.grogan1

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #2 on: August 11, 2016, 08:42:24 AM »
Post mash is the gravity of the combined runnings from the wort collected from the mash.  Pre-boil gravity reflects the gravity of the wort from the mash PLUS any additions of extract or sugars made before the boil starts.

That makes sense.  So if I don't add anything between the mash and boil, they will be the same.

Offline The Little Red Brewster

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #3 on: November 14, 2018, 05:31:31 AM »
Post mash is the gravity of the combined runnings from the wort collected from the mash.  Pre-boil gravity reflects the gravity of the wort from the mash PLUS any additions of extract or sugars made before the boil starts.

My recipe is not adding any sugars before the boil yet it shows a discrepancy between these two figures, confusing.

Offline dtapke

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #4 on: November 14, 2018, 08:55:08 AM »
Can you upload your recipe or a picture?
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Offline Kevin58

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #5 on: November 14, 2018, 09:11:40 AM »
Post mash is the gravity of the combined runnings from the wort collected from the mash.  Pre-boil gravity reflects the gravity of the wort from the mash PLUS any additions of extract or sugars made before the boil starts.

My recipe is not adding any sugars before the boil yet it shows a discrepancy between these two figures, confusing.

Discrepancy high or low? Are you adding top off water?
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Offline Oginme

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #6 on: November 14, 2018, 09:32:23 AM »

My recipe is not adding any sugars before the boil yet it shows a discrepancy between these two figures, confusing.

Export the recipe as a .bsmx file and upload it to this thread so we can look and diagnose the issue.
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Offline AJAlexander

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #7 on: May 24, 2020, 08:19:04 AM »
I came across this as I was wondering what the difference between these two numbers were as well.  I don't normally add anything before the boil.  I always do BIAB, however I end up adding extra water between the mash and boil as my kettle is not big enough to handle the full volume of water plus my grains.

Should I be taking two seperate measurements before the water top up, and after water top up?  Either way, would my numbers be the same and if not would the later be my "Meas Pre-Boil Gravity"?

Thanks!

Offline Oginme

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Re: Measure post mash gravity vs Pre boil gravity
« Reply #8 on: May 24, 2020, 09:03:09 AM »
The answer in the end is it is up to you.  If you want to help with diagnosing issues of low gravity from the mash or to get a better idea of what your mash efficiency versus your brew house efficiency, then you can take a gravity measurement before you add the top off water and put that number in the 'meas post mash gravity'. Then after you add your top off water you can take another reading for your 'meas pre boil gravity.

If you don't want to go through the extra measurement, then don't. 
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