So that would be after the grain bag has been removed (after mash out at 75)) ?I take a pre-boil gravity sample when my kettle is at the pre-boil volume. When I have that I know my ending boil gravity.
It has as it has changed the way I need to do things - again thanks to allEveryone here has had some kick ass input, I really hope something resonated with you that is going to bring your brewing to the next level!
Do you take the Pre-Boil Gravity reading after the 60 min mash or after the 75C 10min Mash Out ?
I agree with the others...Pre-Boil Gravity is the gravity of the full amount of wort just before the boil starts. Note that BeerSmith has a Post-Mash Gravity and a Pre-Boil Gravity. The difference being that Pre-Boil contains sugars added into the boil. I suspect other software have similar measures.
I am a BIAB brewer. I will normally take a quick volume and gravity reading after I have pulled the bag and it has drained for a few minutes. At this point I can still adjust if I am a little high or low on volume or gravity (say stop draining if I am at my targets, squeeze the bag if I need more volume or gravity points, etc.). I will then usually take the "official" pre-boil reading just before the boil starts. If needed, I could adjust the length or vigor of my boil based on my pre-boil gravity and volume.
A refractometer helps a lot with this. For many years I only took a gravity reading when I was transferring chilled wort into the fermenter. That works as well, and I still always ended up with beer in the end!
This is so ridiculously simple but clever to take the leftover, adjust to 1040, and can it. Wish I thought of that myselfI have a higher mash efficiency than my recipes require, which works to my advantage. I lauter more than I need into multiple pots (drives my wife nuts) and then I get the readings of each. Then I blend them to get the pre-boil gravity exactly where I want it since my boil off rate is always the same. The left over wort is adjusted to 1040 with either water or DME and pressure canned in quart jars for future starters. It sounds more complicated than it actually is and has resulted in me being more satisfied with my beers.
Agree my rate is also very low (I squeeze hard) but interesting to read about your theory on mash-outs, thanksThis is so ridiculously simple but clever to take the leftover, adjust to 1040, and can it. Wish I thought of that myself
@UdonPete - Everybody else is right. If you are BIAB then the pre-boil gravity is what you have after you pull the bag and drain or squeeze. It's the final volume you have directly before the boil. @CascadesBrewer gave some good advice above as well. I see you read that. You can always adjust by topping up with some water or adjusting the boil.
If you're dialing in your system then also keep in mind the grain absorption rate. That's going to affect your pre-boil volume which, in turn, is going to affect your pre-boil gravity. Some of the estimates out there are pretty off for grain absorption but there are a few useful HBT threads that take polls of BIAB users and should get you to a good initial starting number for absorption rate. For example, I squeeze pretty hard and have a rate of about .08 gal/lb. Note your pre-mash and post-mash volumes for a few brews and figure out your grain absorption rate. That constant will drive you mash water volume and get you to the point where you aren't always adjusting your pre-boil too much to get your numbers right. If you're BIAB then you really might not need that mash out either. I have never seen a convincing argument for doing a mash out, especially for BIAB, but maybe I am missing something there.
Good luck! You'll dial in to your setup with some care and attention and things always get much smoother and more consistent.
^^^This^^^I take pre boil gravity readings when all the wort is in the boil kettle before the boil begins.
Only 2 points difference after boiling? This does not sound very likely.^^^This^^^
We take a gravity reading when the boil kettle is full, prior to starting the boil.
There is not always a huge difference in the readings, however.
Pre-boil gravity: 1.052 / Brix: 12.6
OG: 1.054 / Brix: 13.0
Only 2 points difference after boiling? This does not sound very likely.
that is going to bring your brewing to the next level!
You're right, but I didn't want to discourage hahaha. He's gotta find that out the hard way!and then back down again!
This- I take mine post sparge once I'm at full preboil.I take pre boil gravity readings when all the wort is in the boil kettle before the boil begins.
Surely it depends how long you boil for, and on your evaporation rate? I've frequently only seen a 3-4 point change between preboil and OG when I'm doing a 30m boil, particularly with lower gravity beers.Only 2 points difference after boiling? This does not sound very likely.
You are defying the laws of physics. Not possible.The readings, both pre and post boil, were accomplished with a refractometer.
The line in the sight gauge was well defined, and easy to read. I double checked, just to be sure.
Nothing so nefarious as stratification would occur at Bel Air.
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