# Mash

Discussion in 'Calculator Support Forum' started by erkki, Apr 22, 2020.

1. ### erkki New Member

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#1
Where do I find the post mash Numbers so that I know that the mash is Done? Not the pre boil, but before I start to Sparge? I see Brewers mesure wort gravity from the mash but where do I find the reading it should be?

2. ### The Brew Mentor Well-Known Member

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#2
Hi erkki,
No calculator is going to tell you when the mash is "done".
The recipe builder will give you the pre-boil gravity based on what you input as far as efficiency and water usage. The problem is that that number would be based on your pre-boil volume. Unless you're doing a full volume no sparge, that number won't match your concentrated wort reading.

Knowing when your mash is done requires information about it, such as;
What is the PH of the water.
What is the PH of the mash.
What is the Grain bill.
What temperature did you mash at.
How long did you mash for.

The main factors are time and temperature.

A simple way to have assurance that the mash is ready to sparge and go forward to boil is an Iodine test.
Simply take a tablespoon of clear wort from your mash and put it onto a white saucer. Then put a drop of Iodine onto it. If it turns black, you're not finished. If it stays red, you can move on.

Although most of today's highly modified grain will convert in about 15 minutes in the proper conditions, most Brewer's have and continue to mash for 1 hour.
Early on in my brewing, I just tried to hit my mash temperature and mashed for an hour.
You know what? It always made beer!
Have fun, read and learn from each batch, and RDWHAHB!
Cheers,
Brian

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3. ### erkki New Member

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#3
Great

4. ### erkki New Member

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Thanks, I know about the idoin test and probably Will start using that. Why I ask is that I saw a brewer on youtube who always take a gravity reading to see if his mash is finished and he calls it his pre boil gravity?? For me pre boil is what I have in the boil kettle before boil. It made me curious Any way great answer ! Cheers

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5. ### Craigerrr Well-Known Member

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#5
Even I can post videos on the interwebs!

6. ### Craigerrr Well-Known Member

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#6
What I mean is one video is not gospel, and there are as many ways to make beer as there are brewers. Watch a lot of videos and find what works best for you.

7. ### erkki New Member

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8. ### Pricelessbrewing QA Software Tester Staff Member

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Im going to disagree with you there @The Brew Mentor.

You should be able to predict your mash gravity or presparge gravity using your typical conversion efficiency, and the recipes information about grain bill, and mash thickness.

Conversation efficiency is very stable and not prone to the fluctuations based on OG like brewhouse or kettle/mash. Typically conversion efficiency is somewhere between 88-94%.

A typical 1.055 OG, 12 lb recipe with no kettle or mashtun losses other than grain absorption (0.125 qt/lb) would be around 1.069 at mash.

Once you reach ~90% conversion efficiency, your mash is likely done. The conversion efficiency can be calculated in the brewsession via the "mash complete" log entries.

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9. ### The Brew Mentor Well-Known Member

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#9
Interesting, where exactly is this calculator?
I'm not seeing it and want to try it out.
Cheers,
Brian

10. ### Pricelessbrewing QA Software Tester Staff Member

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#10
There's no BF calculator currently that will estimate or predict the mash SG, but the brew sessions has a log entry for "mash complete" which will give you your conversion efficiency based on a gravity sample, and the amount of water used (basically your mash thickness determines the maximum possible gravity based on the grains used). There is some discussion on introducing this feature, but will require some work on the mash guidelines section.

Here's my example recipe and brew session entries.
https://www.brewersfriend.com/homebrew/recipe/view/968382/test-conversion-efficiency/333568

Which gives you the conversion efficiency here,