Mash Thickness and Efficiency

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Yeah, so I'm getting ready to do a kitchen sink stout with all of my leftover specialty grains. If the brewer's friend calculator is to be believed, the black patent and especially the chocolate wheat are going to make my pH way too low (4.2 instead of 5.3). I want them mostly for color anyway, so I guess I could just steep them separately. But when should I add that tea to the wort to avoid screwing things up?
Can't you adjust in the water calculator? Baking soda should do the trick I'd think...
 
It might be a mash pH thing. Dark roasted grains are inherently acidic. If a pale beer turns out fine but a dark beer has lower efficiency, consider whether your mash pH might have fallen down to 4.9-5.1 or something like that, far from the ideal of 5.3 or more.
It's possible.. But my target was 5.5 and my final reading at the end of the mash was 5.52.

It was 5.4 after 10 minutes, but interestingly, I had an online chat with Denny Conn and he said mash pH readings should be taken at the end of the mash to be most accurate.
 
@SRJHops
Perhaps consider a reiterated mash.
For the reiterated, I just watched a few videos... Some people also sparge a bit and use that water too for the second mash. But others just use the mash wort only for the second mash. That seems easier... Is one method better?

I also see people removing the spent grains before putting in the rest (other half) of the grains. If all the grains will fit in the tun, could I just keep the old and new grains in there together?
 
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Dark grains need not affect mash pH at all if you steep them separately, then move the resulting liquid to the kettle. Also, consider Carafa® in place of black patent for less bite.

Happy brewing!
 
Dark grains need not affect mash pH at all if you steep them separately, then move the resulting liquid to the kettle.
Right. As in my first post in this thread.

Also, consider Carafa® in place of black patent for less bite.
I guess you also missed the part about the point of this brew being to use up all of my leftover specialty grains. :D
 
That's a great idea! Have you done it? I bet even 30 minutes would do the trick? Or do you think I should do another full hour... My brew day is getting pretty long!
Yes I did one for the first barley wine that I made in my robobrew 3. It was a while ago now. I followed the method on a youtube video, possibly david heath youtube video. It did add time to the day but a lot quicker than the stuck mash and sparge I got from having the rye grains milled to perfectly block every hole in the bottom plate of my malt pipe on my 70litre all in one.
 
Right. As in my first post in this thread.


I guess you also missed the part about the point of this brew being to use up all of my leftover specialty grains. :D
Mac, I mentioned the timing of the result of steeping because @dmtaylor suggested you could add it near the end of the mash with other stuff. And 'cuz you asked about timing. The other thing is for some future batch I guess. Enjoy the leftovers;)
 
I have read conflicting things about mash thickness and efficiency. One source said that to improve efficiency I should mash thicker, while another source (see below) says a thinner mash increases the yield.

Yesterday I mashed a big Belgian Quad and got abysmal efficiency, around 55% (I usually get at least 70%). While I usually shoot for 1.75 qt/lb water for the mash, for that one I did 1.28 qt/lb because it was pushing the limits of my tun/system. Now I wish I would have increased the water to 1.75 qt/lb at least. I even mashed for two hours...

So why would folks suggest that a thicker mash could improve efficiency? I did see a post that said to mash thick so you can collect more sugar during the sparge. That did not make any sense to me, unless perhaps the person was fly sparging? I batch sparge. So I'm thinking if I can get most of the sugar from the first runnings, then top off with sparge water, that's a good way to go...

Here's the article saying a Thinner mash is better: Mashing, Thick or Thin? - Brewer's Friend

Would it have been a good idea to mash my Quad at 1.75 qt/lb or even 2 qt/lb?
Mash thickness affects the rate of conversion, with thinner mashes converting faster than thicker mashes. So, if you mash for a fixed time, that is not long enough to get 100% conversion, then a thinner mash will have better conversion efficiency than a thicker mash.

Conversion efficiency is only half the story however. Mash efficiency equals conversion efficiency times lauter efficiency. When fly sparging, lauter efficiency is improved by mashing thicker and using more water for sparging (for a fixed pre-boil volume). When batch sparging, lauter efficiency is maximized when all the run-offs (initial and all sparges) have equal volume. Because of grain absorption, in order to get equal run-off volumes, the strike volume needs to be greater than each of the sparge volumes.

To figure optimal strike and sparge volumes for batch sparging use the following formulas:
Each sparge step volume = pre-boil target volume / (1 + number of sparge steps)​
Strike volume = one sparge step volume + expected total grain absorption​
A simple rule of thumb for volumes when single batch sparging is 60% of total water required for strike, and 40% for sparge. If double batch sparging then use 50% - 25% - 25%. When doing batch sparging you shouldn't even think about hitting a specific mash thickness.

Things get a little trickier when batch sparging large grain bills. If the mash thickness from using the guidance in the previous paragraph results in a mash that is too thick to stir effectively, then you will need to shift water from sparge to strike. This is the only time you should worry about mash thickness when batch sparging.

Brew on :mug:
 
Mash thickness affects the rate of conversion, with thinner mashes converting faster than thicker mashes. So, if you mash for a fixed time, that is not long enough to get 100% conversion, then a thinner mash will have better conversion efficiency than a thicker mash.

Conversion efficiency is only half the story however. Mash efficiency equals conversion efficiency times lauter efficiency. When fly sparging, lauter efficiency is improved by mashing thicker and using more water for sparging (for a fixed pre-boil volume). When batch sparging, lauter efficiency is maximized when all the run-offs (initial and all sparges) have equal volume. Because of grain absorption, in order to get equal run-off volumes, the strike volume needs to be greater than each of the sparge volumes.

To figure optimal strike and sparge volumes for batch sparging use the following formulas:
Each sparge step volume = pre-boil target volume / (1 + number of sparge steps)​
Strike volume = one sparge step volume + expected total grain absorption​
A simple rule of thumb for volumes when single batch sparging is 60% of total water required for strike, and 40% for sparge. If double batch sparging then use 50% - 25% - 25%. When doing batch sparging you shouldn't even think about hitting a specific mash thickness.

Things get a little trickier when batch sparging large grain bills. If the mash thickness from using the guidance in the previous paragraph results in a mash that is too thick to stir effectively, then you will need to shift water from sparge to strike. This is the only time you should worry about mash thickness when batch sparging.

Brew on :mug:
What a great explanation! I fly sparge and mash generally around 1.1qt. I tend to mash long and sparge slow. My brew sessions are longer, but my large batches and low/high gravity end with the same efficiency. I generally underlet and mix to start, and never open the tun until sparge is complete. Really a great explanation, I was wondering when you would show big D! 😎👏🏼👏🏼
 
Mash thickness affects the rate of conversion, with thinner mashes converting faster than thicker mashes. So, if you mash for a fixed time, that is not long enough to get 100% conversion, then a thinner mash will have better conversion efficiency than a thicker mash.

Conversion efficiency is only half the story however. Mash efficiency equals conversion efficiency times lauter efficiency. When fly sparging, lauter efficiency is improved by mashing thicker and using more water for sparging (for a fixed pre-boil volume). When batch sparging, lauter efficiency is maximized when all the run-offs (initial and all sparges) have equal volume. Because of grain absorption, in order to get equal run-off volumes, the strike volume needs to be greater than each of the sparge volumes.

To figure optimal strike and sparge volumes for batch sparging use the following formulas:
Each sparge step volume = pre-boil target volume / (1 + number of sparge steps)​
Strike volume = one sparge step volume + expected total grain absorption​
A simple rule of thumb for volumes when single batch sparging is 60% of total water required for strike, and 40% for sparge. If double batch sparging then use 50% - 25% - 25%. When doing batch sparging you shouldn't even think about hitting a specific mash thickness.

Things get a little trickier when batch sparging large grain bills. If the mash thickness from using the guidance in the previous paragraph results in a mash that is too thick to stir effectively, then you will need to shift water from sparge to strike. This is the only time you should worry about mash thickness when batch sparging.

Brew on :mug:
This is excellent info - thanks!

For the Quad I actually did do 60% water for the mash and 40% for the sparge.

Why do the big beers often have lower efficiency?

I am now thinking anytime I am shooting for 1.080 OG or higher I'd better change my process...

The next time I brew a big beer, I think I will mash a bit thinner, do a reiterated mash, increase the sparge water, and plan for a 2 hour boil. That should hopefully do the trick and/or be good learning!
 
This is excellent info - thanks!

For the Quad I actually did do 60% water for the mash and 40% for the sparge.

Why do the big beers often have lower efficiency?

I am now thinking anytime I am shooting for 1.080 OG or higher I'd better change my process...

The next time I brew a big beer, I think I will mash a bit thinner, do a reiterated mash, increase the sparge water, and plan for a 2 hour boil. That should hopefully do the trick and/or be good learning!
As beers get bigger, you need more grain, and the result is a larger fraction of the total wort stays in the spent grain due to absorption. This is why lauter efficiency drops off as grain bills get larger. The effect can be calculated with high accuracy for batch sparging, and estimated with reasonable accuracy for fly sparging (by using many small batch sparges to simulate a fly sparge.) If you plot efficiency vs. the ratio of grain bill weight to pre-boil volume, you remove the batch size as a factor.

For batch sparging the lauter efficiency vs. grain bill ratio looks like this:

Efficiency vs Grain to Pre-Boil Ratio for Various Sparge Counts.png


The calculations are for the case of equal run-off volumes (unless that would force the mash to be thicker than 0.9 qt/lb), so mash thickness varies as required to maintain equal run-off volumes (when possible.)

For fly sparging, I simulate the fly sparge with 15 small batch sparges, and set specific starting mash thicknesses. As the grain bill gets larger, the amount of strike water increases to maintain the chosen mash thickness, and the amount of sparge water decreases. Here is what lauter efficiency variation looks for fly sparging:

Fly Sparge Eff vs Grain to Pre-boil Ratio.png

This chart shows that lauter efficiency goes up across the board as the mash gets thicker, due to allowing more water for sparging. The lines terminate at the right when the strike water required to maintain target mash thickness would cause the pre-boil volume to be exceeded (which would also mean 0 sparge water.)

The curve shapes a bit different for batch sparging vs. fly sparging, but the decrease in lauter efficiency with increasing grain bill weight holds for both processes.

You can gain back some lauter efficiency by targeting a larger pre-boil volume, with the intention of boiling off the excess water to obtain the target batch size.

Another interesting chart is to plot lauter efficiency vs. OG. For the chart below, a fixed batch size (5.5 gal post-boil volume and 5.0 gal fermenter volume) was assumed, along with a constant boil-off volume (1.0 gal.) Note that lauter efficiency drops off faster with increasing OG than it does with increasing grain bill ratio. This is because the decreasing efficiency increases the amount of grain required, shifting you even further to the right on the grain bill ratio axis.

Efficiency vs OG.png

Brew on :mug:
 
The reason I said it is that I am a batch sparger too, BUT... I was double-sparging, dividing the mash volume and the two sparge volumes equally into not just two but THREE equal portions. Equalizing the volumes results in maximum batch sparge efficiency.

If I understand.... For your process you are using twice as much sparge water as mash water, then collecting a larger pre-boil volume and boiling longer.

A simple rule of thumb for volumes when single batch sparging is 60% of total water required for strike, and 40% for sparge. If double batch sparging then use 50% - 25% - 25%.

Just to add... if we do the volumes and concentrations math, we find that the highest lauter efficiency when batch sparging is obtained when all of the runnings volumes are equal to each other, and not where each of the sparge volumes equals the strike volume, because grain absorption matters. @doug293cz's rule of thumb will typically yield something pretty close to that, given reasonable (i.e. "real life" recipe/brewhouse) inputs.
 
As beers get bigger, you need more grain, and the result is a larger fraction of the total wort stays in the spent grain due to absorption. This is why lauter efficiency drops off as grain bills get larger. The effect can be calculated with high accuracy for batch sparging, and estimated with reasonable accuracy for fly sparging (by using many small batch sparges to simulate a fly sparge.)

A while back, a local brewery asked me to help them fix a problem related to low lauter efficiency on their really high gravity beers on their pilot system. I did something similar to your series of small batch sparges to simulate their fly sparge. Of course, the "problem" wasn't really a problem. It was just physics. The "fix" was a longer sparge (i.e. more water), with a longer boil. They couldn't throw more grain at it, due to the size of their pilot system's mash tun.
 
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Just to add... if we do the volumes and concentrations math, we find that the highest lauter efficiency when batch sparging is obtained when all of the runnings volumes are equal to each other, and not where each of the sparge volumes equals the strike volume, because grain absorption matters. @doug293cz's rule of thumb will typically yield something pretty close to that, given reasonable (i.e. "real life" recipe/brewhouse) inputs.
This is correct. Thanks for the clarification; I was not this clear in my initial response. The grains soak up a lot of wort permanently, so for highest efficiency, with a batch sparge, the volume that matters for the first part out of the mash is the runnings, not the entire volume of the mash.

For more of a real-world example, for 5 to 6 gallons of final wort, if you were to use say 20 lbs of grain for a monstrous gravity beer AND wanted excellent efficiency close to 80%...

Well first of all, the 20 lb grain will soak up about 2 gallons of water permanently. So if you wanted, say, 9 gallons pre-boil (maybe you're planning to boil for 3 hours), and wanted to divide that 9 gallons 3 ways for optimal double-sparge after the mash, you would actually need about 11 gallons of pre-mash water total, using 5 gallons strike water in the mash (approx 1.0 qt/lb!), and 3 gallons for each sparge (times 2 for double sparge). This will maximize the efficiency you can get from a double sparge in a big beer. This is precisely the method I use for monster beers. I have gotten brewhouse efficiency in the 80s with big beers before. It IS possible, with a big sparge volume and very long boil to concentrate it down.

Looks like Doug's percentages of 50/25/25 are reasonable approximations, maybe a little swaggy, but would put you into a decent ballpark. You can get pretty darn good efficiency with that ratio.

You might notice I don't separate mash efficiency vs. lauter efficiency. I use brewhouse which is a combination of the two. If you aren't crushing your grains enough, your brewhouse efficiency is always going to suck compared to what it could be if you crushed better. If you aren't collecting every drop of wort but leaving a lot behind, your brewhouse efficiency is going to suck. If you want to maximize efficiency, crush well, and collect all the sugar. Leave almost zero starch or sugars behind, whatever it takes. That's what it's all about. If you don't care about any part of this, or your equipment can't handle it, your efficiency might never hit the 80s or 90s. That's fine, that's OK. But don't expect it to get real high if your equipment or process can't handle it.
 
This is correct. Thanks for the clarification; I was not this clear in my initial response. The grains soak up a lot of wort permanently, so for highest efficiency, with a batch sparge, the volume that matters for the first part out of the mash is the runnings, not the entire volume of the mash.

For more of a real-world example, for 5 to 6 gallons of final wort, if you were to use say 20 lbs of grain for a monstrous gravity beer AND wanted excellent efficiency close to 80%...

Well first of all, the 20 lb grain will soak up about 2 gallons of water permanently. So if you wanted, say, 9 gallons pre-boil (maybe you're planning to boil for 3 hours), and wanted to divide that 9 gallons 3 ways for optimal double-sparge after the mash, you would actually need about 11 gallons of pre-mash water total, using 5 gallons strike water in the mash (approx 1.0 qt/lb!), and 3 gallons for each sparge (times 2 for double sparge). This will maximize the efficiency you can get from a double sparge in a big beer. This is precisely the method I use for monster beers. I have gotten brewhouse efficiency in the 80s with big beers before. It IS possible, with a big sparge volume and very long boil to concentrate it down.

Looks like Doug's percentages of 50/25/25 are reasonable approximations, maybe a little swaggy, but would put you into a decent ballpark. You can get pretty darn good efficiency with that ratio.

You might notice I don't separate mash efficiency vs. lauter efficiency. I use brewhouse which is a combination of the two. If you aren't crushing your grains enough, your brewhouse efficiency is always going to suck compared to what it could be if you crushed better. If you aren't collecting every drop of wort but leaving a lot behind, your brewhouse efficiency is going to suck. If you want to maximize efficiency, crush well, and collect all the sugar. Leave almost zero starch or sugars behind, whatever it takes. That's what it's all about. If you don't care about any part of this, or your equipment can't handle it, your efficiency might never hit the 80s or 90s. That's fine, that's OK. But don't expect it to get real high if your equipment or process can't handle it.

When you say that's the process you use, do you really use a mash thickness of 1.0 qt/lb? That's really getting low...

Could I ask your opinion about the reiterated mash? Maybe it's not really necessary if I do the 50-25-25 with the double batch sparge?
 
As beers get bigger, you need more grain, and the result is a larger fraction of the total wort stays in the spent grain due to absorption. This is why lauter efficiency drops off as grain bills get larger. The effect can be calculated with high accuracy for batch sparging, and estimated with reasonable accuracy for fly sparging (by using many small batch sparges to simulate a fly sparge.) If you plot efficiency vs. the ratio of grain bill weight to pre-boil volume, you remove the batch size as a factor.

For batch sparging the lauter efficiency vs. grain bill ratio looks like this:

View attachment 812768

The calculations are for the case of equal run-off volumes (unless that would force the mash to be thicker than 0.9 qt/lb), so mash thickness varies as required to maintain equal run-off volumes (when possible.)

For fly sparging, I simulate the fly sparge with 15 small batch sparges, and set specific starting mash thicknesses. As the grain bill gets larger, the amount of strike water increases to maintain the chosen mash thickness, and the amount of sparge water decreases. Here is what lauter efficiency variation looks for fly sparging:

View attachment 812771
This chart shows that lauter efficiency goes up across the board as the mash gets thicker, due to allowing more water for sparging. The lines terminate at the right when the strike water required to maintain target mash thickness would cause the pre-boil volume to be exceeded (which would also mean 0 sparge water.)

The curve shapes a bit different for batch sparging vs. fly sparging, but the decrease in lauter efficiency with increasing grain bill weight holds for both processes.

You can gain back some lauter efficiency by targeting a larger pre-boil volume, with the intention of boiling off the excess water to obtain the target batch size.

Another interesting chart is to plot lauter efficiency vs. OG. For the chart below, a fixed batch size (5.5 gal post-boil volume and 5.0 gal fermenter volume) was assumed, along with a constant boil-off volume (1.0 gal.) Note that lauter efficiency drops off faster with increasing OG than it does with increasing grain bill ratio. This is because the decreasing efficiency increases the amount of grain required, shifting you even further to the right on the grain bill ratio axis.

View attachment 812772
Brew on :mug:

This is really great stuff - thank you! It may take me a while to digest all the charts, but this is excellent learning for me.

As I digest it all, could I ask if this sentence you wrote is accurate? I've read it a few times and I'm still processing it: "The effect can be calculated with high accuracy for batch sparging, and estimated with reasonable accuracy for fly sparging (by using many small batch sparges to simulate a fly sparge.)"

My big take-away is that I need to do more than one sparge, at least for beers over 1.080 OG. I will try the 50-25-25, splitting the sparge water in half and doing two. But it looks you do 15 small ones? There must be diminishing returns, but you have determined that 15 is about right?

Personally, I almost always hit my 70% efficiency goal with one sparge, but I clearly need to change my process for big beers. (I'm not really chasing higher efficiencies -- I just want to be at the same efficiency so I hit my numbers.)
 
My big take-away is that I need to do more than one sparge, at least for beers over 1.080 OG. I will try the 50-25-25, splitting the sparge water in half and doing two. But it looks you do 15 small ones? There must be diminishing returns, but you have determined that 15 is about right?

@doug293cz isn't doing 15 real batch sparges. He's modeling 15 batch sparges, in a spreadsheet, to approximate a fly sparge, which would otherwise require some fairly advanced math, not to mention some more assumptions, which may not hold true (or be worth the effort).
 
@doug293cz isn't doing 15 real batch sparges. He's modeling 15 batch sparges, in a spreadsheet, to approximate a fly sparge, which would otherwise require some fairly advanced math, not to mention some more assumptions, which may not hold true (or be worth the effort).

So just two batch sparges then? 50-25-25 for the water?
 
I'd say that's a good place to start, if you don't want to go to the trouble of calculating equal runoffs.
I'll have to do a bit more thinking on the runoff volumes. I have never written down the totals, though the info is right in front of me as the kettle fills.

For now I think I will shoot for 60% mash water and 40% sparge. I might add a touch more mash water to get my thickness to 1.50 or 1.75. I get that it may not matter much, but my gut tells me that for my process it may help.
 
I'll have to do a bit more thinking on the runoff volumes. I have never written down the totals, though the info is right in front of me as the kettle fills.

If you want to calculate it, @dmtaylor gave an example in post #56. Basically, take your total water and subtract the wort volume that will be left behind in the mash tun (because of absorption and (if applicable) dead space). The result is your pre-boil volume. Divide that pre-boil volume by 3. That gives you the equal amount to run off at each stage.

Your strike water will be equal to: Total Water Minus pre-boil volume, plus 1st equal runoff
Your first batch sparge will be equal to the 2nd equal runoff
Your second batch sparge will be equal to the 3rd equal runoff

I think near the top of this thread you mentioned running off until you reach your pre-boil volume. But you should calculate the total water needed and use that. If you are leaving water/wort in the mash tun beyond grain absorption and any unrecoverabe dead space, you won't get an efficient batch sparge.

For now I think I will shoot for 60% mash water and 40% sparge. I might add a touch more mash water to get my thickness to 1.50 or 1.75. I get that it may not matter much, but my gut tells me that for my process it may help.

If you are getting near 100% conversion efficiency, your most efficient batch sparge strategy for any given total water volume will be equal runoffs, regardless of what your gut tells you.
 
double sparge? why not just a bigger, longer sparge?

Or are you, closing the mash tub drain after the first run off, re-filling with sparge water, stirring it up a bunch, then drain. And then repeat again?

I've been BIAB and using less and less mash water, but then just pulling the basket and rinsing/sparging the grain longer.
 
Does soaking the "spent" drained grain for a bit get more sugars out than just rising/sparging it after the initial drain to kettle?

Or is that what "batch sparge" vs "flysparge" is? I kinda forget the details.
 
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If you want to calculate it, @dmtaylor gave an example in post #56. Basically, take your total water and subtract the wort volume that will be left behind in the mash tun (because of absorption and (if applicable) dead space). The result is your pre-boil volume. Divide that pre-boil volume by 3. That gives you the equal amount to run off at each stage.

Your strike water will be equal to: Total Water Minus pre-boil volume, plus 1st equal runoff
Your first batch sparge will be equal to the 2nd equal runoff
Your second batch sparge will be equal to the 3rd equal runoff

I think near the top of this thread you mentioned running off until you reach your pre-boil volume. But you should calculate the total water needed and use that. If you are leaving water/wort in the mash tun beyond grain absorption and any unrecoverabe dead space, you won't get an efficient batch sparge.



If you are getting near 100% conversion efficiency, your most efficient batch sparge strategy for any given total water volume will be equal runoffs, regardless of what your gut tells you.
I think I really do need to dig into the water calcs more for sure. I did increase the water for this beer, but it was just a guess. I did leave some wort in the sparge tun, maybe a quart or two. So that was clearly a mistake.

I still question If I am getting close to 100% conversion efficiency in the mash, though.

Maybe even with the 2 hour mash I might not have gotten full conversion? Or why do people do reiterated for big beers?

Perhaps reiterated isn't really a very good process improvement? I did watch one video where it didn't work....
 
Have to congratulate everyone this has been a very instructive thread.
I'm going to have to read it another ten times I think to come up with a big grain bill high gravity beer plan.
Thanks to all
 
Maybe even with the 2 hour mash I might not have gotten full conversion? Or why do people do reiterated for big beers?

With sufficient enzymes (check the net Lintner => 40), fluidity, endosperm availability and reasonable temperatures, a mash will likely have fully converted within the first 40 minutes or less. That said, "conversion" just means transformation from the base starches to compounds which may or may not be fully fermentable. Prolonging the mash duration can allow time for unfermentable dextrins to be degraded into fermentable sugars.

Iterative mashing is often used to produce the wort density desired when working with a "too small" mash tun...

Cheers!
 
With sufficient enzymes (check the net Lintner => 40), fluidity, endosperm availability and reasonable temperatures, a mash will likely have fully converted within the first 40 minutes or less. That said, "conversion" just means transformation from the base starches to compounds which may or may not be fully fermentable. Prolonging the mash duration can allow time for unfermentable dextrins to be degraded into fermentable sugars.

Iterative mashing is often used to produce the wort density desired when working with a "too small" mash tun...

Cheers!
So if I can fit all my grain in my tun, there is no real point of reiterated mashing, correct?
 
Well, that and fitting enough wort in your kettle.
As an example, if you wanted to brew 5 gallons of a 110 point stout and your gear will mash, lauter and boil enough grain to hit those numbers there'd be no reason for iteration...

Cheers!
 
Well, that and fitting enough wort in your kettle.
As an example, if you wanted to brew 5 gallons of a 110 point stout and your gear will mash, lauter and boil enough grain to hit those numbers there'd be no reason for iteration...

Cheers!
So a reiterated mash doesn't help with mash conversion efficiency. It's for folks who can't fit all their grain in their tun.

My grain did all fit, and I could add more wort to my kettle for the boil off. I have been in the habit of boiling 7 gallons, which has worked for every beer but the Quad. But I could fit at least another gallon in my 10 gallon kettle.

Going forward I am going to calculate my water volumes better. I will also do a double sparge for all my beers!

Great advice all - thank you!
 
I think as the mash gets "thicker", the enzymes have to work harder to convert all starch to sugar, or it hits a "wall" and stops short.

I believe a thinner mash helps achieve full conversion, but then you will have a greater volume/lower SG wort to deal with (boil down).

Once you drain off the mash and start sparging...it's all the same "thickness" I would think
I think that sounds right.
EDIT: I don't believe the enzymes "work" harder, it just becomes a question can they be as effective in a more viscous liquid.
But I will add that if you have multiple grains in the mash and you are relying on a particular grain with a high diastatic value to help convert perhaps a larger volume of grain with a low diastatic value, there is a balance to be struck in-order to ensure the enzymes from the higher diastatic grain get distributed to where they are needed. So it seems like sufficient water and sufficient motion would help.
Just a theory
 
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hey @doug293cz , is there a therorectical limit to grain water? i know you did the batch sparge itteration chart before? maybe be handy for this thread....

maybe something similar for fly sparging? if i've seen it already and forgotten sorry.....
 
As I digest it all, could I ask if this sentence you wrote is accurate? I've read it a few times and I'm still processing it: "The effect can be calculated with high accuracy for batch sparging, and estimated with reasonable accuracy for fly sparging (by using many small batch sparges to simulate a fly sparge.)"
Yes, I was very careful about how I worded that sentence. For batch sparging, the calculations are more accurate than the measurements that we can make as typical homebrewers. For fly sparging, the calculations appear, based on limited data, to be about as accurate as the measurements that we make. There are a few conditions that must be met for the calculations to be accurate:
  1. The wort must be completely homogenized throughout the mash volume prior to each run-off. An aggressive stir before each run-off will assure this condition is met.
  2. Conversion of starch to sugar must be complete (or stopped via a mash out) prior to the first run-off, otherwise you will get conversion continuing during the sparge process, and that will mess up the calcs.
  3. Apparent grain absorption must be the same for each run-off. The calculations could be modified to remove this pre-condition, if absorption data were available for each run-off step.
My big take-away is that I need to do more than one sparge, at least for beers over 1.080 OG. I will try the 50-25-25, splitting the sparge water in half and doing two. But it looks you do 15 small ones? There must be diminishing returns, but you have determined that 15 is about right?
Yes, there are diminishing returns for each additional batch sparge step. When doing an actual batch sparge, more that two or three sparge steps doesn't seem worth the effort. As @VikeMan said, the 15 sparge steps is just a way to approximate a continuous (fly) sparge in order to make the calculations tractable. I settled on 15, because with the diminishing returns, the results don't change significantly if I use more than that, so it's "good enough", and better than anything else I know of. You would never actually use that many batch sparge steps.

Brew on :mug:
 
hey @doug293cz , is there a therorectical limit to grain water? i know you did the batch sparge itteration chart before? maybe be handy for this thread....

maybe something similar for fly sparging? if i've seen it already and forgotten sorry.....
There is no theoretical limit to the amount of water you can use for mashing and sparging. But there are practical limits based on vessel size, boil time, and energy cost.

Brew on :mug:
 
Just to add... if we do the volumes and concentrations math, we find that the highest lauter efficiency when batch sparging is obtained when all of the runnings volumes are equal to each other, and not where each of the sparge volumes equals the strike volume, because grain absorption matters. @doug293cz's rule of thumb will typically yield something pretty close to that, given reasonable (i.e. "real life" recipe/brewhouse) inputs.

This is correct. Thanks for the clarification; I was not this clear in my initial response. The grains soak up a lot of wort permanently, so for highest efficiency, with a batch sparge, the volume that matters for the first part out of the mash is the runnings, not the entire volume of the mash.

For more of a real-world example, for 5 to 6 gallons of final wort, if you were to use say 20 lbs of grain for a monstrous gravity beer AND wanted excellent efficiency close to 80%...

Well first of all, the 20 lb grain will soak up about 2 gallons of water permanently. So if you wanted, say, 9 gallons pre-boil (maybe you're planning to boil for 3 hours), and wanted to divide that 9 gallons 3 ways for optimal double-sparge after the mash, you would actually need about 11 gallons of pre-mash water total, using 5 gallons strike water in the mash (approx 1.0 qt/lb!), and 3 gallons for each sparge (times 2 for double sparge). This will maximize the efficiency you can get from a double sparge in a big beer. This is precisely the method I use for monster beers. I have gotten brewhouse efficiency in the 80s with big beers before. It IS possible, with a big sparge volume and very long boil to concentrate it down.

Looks like Doug's percentages of 50/25/25 are reasonable approximations, maybe a little swaggy, but would put you into a decent ballpark. You can get pretty darn good efficiency with that ratio.
Here's a chart by Kai Troester (aka Braukaiser) that shows how lauter efficiency varies with the ratio of initial run-off volume to sparge run-off volume for a single batch sparge. As stated many times already in this thread, the maximum occurs when the volume ratio is 50:50. However, the efficiency difference between 60:40 up to 40:60 is only about 0.5% (which is too small for us to measure given the typical accuracy of our measurements.) So, you don't have to geek out (unless you want to) about getting exactly 50:50 or 33.3:33.3:33.3 run-off ratios. My 60:40 and 50:25:25 rules of thumb are designed to keep you on the flat portion of the efficiency curve over a wide range of grain bill sizes.

Lauter Eff vs Run-off ratio Kaiser.png


Brew on :mug:
 
There is no theoretical limit to the amount of water you can use for mashing and sparging. But there are practical limits based on vessel size, boil time, and energy cost.

Brew on :mug:
Maybe what @bracconiere was trying to ask was about a point after which it's silly to keep sparging just to get a tiny additional amount of sugar into the kettle. Not a theoretical limit exactly... but what is a silliness limit?

Brewing in a more intuitive way with less regard for "hitting numbers," I have sometimes continued sparging until the liquid going into the kettle has no apparent sweetness -- i.e., before it becomes astringent tasting.
 
Maybe what @bracconiere was trying to ask was about a point after which it's silly to keep sparging just to get a tiny additional amount of sugar into the kettle. Not a theoretical limit exactly... but what is a silliness limit?

Brewing in a more intuitive way with less regard for "hitting numbers," I have sometimes continued sparging until the liquid going into the kettle has no apparent sweetness -- i.e., before it becomes astringent tasting.
If you ignore vessel volume limits, then this is really an engineering question that must include costs. When the cost of the additional boil time (both time cost and energy cost) becomes more than the cost of additional grain to make up for the efficiency loss, you have gone too far.

Brew on :mug:
 
There are a few conditions that must be met for the calculations to be accurate:
  1. The wort must be completely homogenized throughout the mash volume prior to each run-off. An aggressive stir before each run-off will assure this condition is met.
  2. Conversion of starch to sugar must be complete (or stopped via a mash out) prior to the first run-off, otherwise you will get conversion continuing during the sparge process, and that will mess up the calcs.
  3. Apparent grain absorption must be the same for each run-off. The calculations could be modified to remove this pre-condition, if absorption data were available for each run-off step.
Aren't most Mash done with conversion in ~30 minutes, at least with today's highly modified grains?
Given that, and it seems true when I test for conversion midway through the mash, if you mash-out at say 60 minutes, you aren't really stopping the conversion are you? Because the modern grains are done long before then.
Don't the equations tend to be aiming for as close to full conversion as is possible with a given grain bill. And in that case they set the mash time based on that time requirement.
Or are they just shotgunning it and saying 60 minutes?🤔
 
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