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Finer crush yielding higher boil volumes?

I recently bought a mill and decided to start double crushing to improve efficiency. Since doing this, my boil volumes are greater than expected. I am very accurate on measuring out malt weights and water volumes, and until now, I could hit very close to my expected boil volume. I use 0.5 quarts (0.125 gallons) of water absorbed per pound of grain. I only factor in 1 quart of dead space in my cooler MLT. The last beers have been bigger ones, so I’m not sure if that’s a factor. I have a difficult time getting much over 70% boil efficiency when I make these big beers which is why I decided to do a double crush. The last beer I brewed I got 79% on a 15lb grain bill for a 5.5 gallon batch, so I did see an improvement, but I was shooting for 6.8 gallons boil volume and got 7.5 gallons. The only thing I can think of is that there is less water absorption with a final crush, or maybe it initially absorbs that much water but then begins to release it at the end of conversion? I know this sounds crazy, but if you have smaller grain pieces and have good conversion of starch to sugar, maybe the spent grain can’t hold all that water anymore? Or is there something else much more obvious going on here?

This would be my guess.



What was yer final yield and volume? That can help to plug in numbers to find out how different a fine crush to a courser crush… Sneezles61

Pre-boil was 1.059 on 7.5 gallons yielding an 82% efficiency. Post-boil was 1.071 on 6 gallons yielding a 79% efficiency. I was shooting for 5.5 gallons, but since I did FWH with the 60 minute hops, I stuck with a 60 minute boil and just boiled harder. The bitterness seems about right when I took a taste racking to secondary this past weekend.

I would think that the efficiency goes up more the water is taken out of the equation… I’ll just do yer numbers later to give an Idea of what I come with… not gospel of course… Sneezles61

Ok, thank you very much for your help.

did you use 15 lbs again? If so, then using 36 points per pound, 1.072, which becomes 100% efficiency… Sneezles61

Am I calculating this incorrectly? This particular beer was a slightly cut down version of Denny’s BVIP. I reduced the grain bill to 15lbs as this pretty much maxes out my 38qt cooler MLT. The recipe shoots for 70% efficiency. I figured if I hit 80% efficiency with 15lbs, I’d be close to the original recipe’s OG. Unfortunately, I didn’t achieve that because I had an extra half gallon of wort at the end of the boil. I kept the grain percentages the same and just reduced the bill across the board. This beer has a number of specialty malts that yield less gravity points, but when I go back into my spreadsheet, the total points that can be achieved is 539 points. So dividing that by the 15lbs of grain, I get an average of 36 points per pound. An OG of 1.071 on 6 gallons is 426 points or 79% efficiency. Am I calculating this totally wrong?

lets do this together. 15 pounds x 36 = 540. Yes 36 is what I find online for points. So then I divide by what yer final volume you are looking for, I’ll use 6. So now you are at 90. I use 80% as my efficiency and that is very close, most of the time, to what I crank out. So then 90 x .8 equals 72. That becomes yer staring gravity, or original gravity. My way isn’t fancy pants, but its how I go about finding/developing a grain bill when I brew. I like to keep things simple. Specialty malts need to be looked up, but won’t give more than 36 PPP… Sneezles61

Yeah, that makes sense. I think we’re just using two different paths to get to the same answer. I thought you were saying in your previous post that 72 points was 100% efficiency. Sorry, I got confused there.

Yeah, that was at 7.5 gallons tho… Sneezles61

Oh, I get the confusion now. The 7.5 gallons was pre-boil. That gravity (BG) was 1.059. That yielded 443 points for an efficiency of 82%. This was all the same batch. I wasn’t comparing two batches. I was just giving you all the numbers on this particular batch. Sorry for not making this clear.

It may be that I’m too simple, I don’t usually look at gravity until its just about to go into the fermenter, then I will test and verify my readings… Sneezles61

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