Squeeze the bag

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Fly_Guy

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I've completely derailed this thread, and I apologize, but how did you figure out the ATC for water?
 

CascadesBrewer

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Nice. I really like the SS ruler idea. Did you put in a gallon of water and use that to figure out where the mm's measured up, or did you use the formula for volume of a cylinder?
My rather crude solution is a handful of "dipsticks" made from chopsticks that I used a permanent marker to mark volumes. The chopsticks are some type of plastic-ish material (the label says "high elephant tusk chopsticks" but they are clearly not elephant tusks). I use a formula to measure out volumes, mark a few with a pencil, verify the measurements with liquid, then mark with the permanent marker. I am sure you could use a variety of materials or items for something similar. I have dip sticks for my 10, two 5 and 3 gallon pots. I have to refresh the marks now and then.

IMG_3303.JPG
 

CascadesBrewer

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On a (almost) related topic. What temp do you measure your strike water?

I measure strike water at "tap" temperature. I know that my tap varies from 55F-ish to 75F-ish, but I don't take the temp into account. I measure my pre-boil and post-boil volume at near boiling temps. I use a grain absorption value of 0.06875 gal/lb (well...I use a value of “0.55 fl oz/oz” which are the units that BeerSmith uses). That value works for me, but I know I measure my strike and pre-boil water at different temps. I know BeerSmith has a "shrinkage %" value, but I have wondered a bit about how it account for an "expansion %" when heating water.

When I first started with BIAB I was squeezing and at first measured an absorption value of 0.05 gal/lb. I started with that for a few batches but found that I was often coming up a little short on volume. I ditched the aggressive squeezing and went for the 0.069 gal/lb value to make brew day easier and more predictable. At the same time I dropped my target overall efficiency from 75% to 73%.
 

DBhomebrew

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I don't account for varying 'room temps' or 'strike/mash temps' either. 'Pitch temp' is lumped in with 'room temp' too, even though it's typically 10° lower. I'll probably figure out another percentage value for 'kviek pitch temp'.

I measure strike and sparge volumes at room temp. 1st runnings at mash temp. Preboil just before boil (having let the bag free hang for that time). Post-boil at flameout. Chilled volume at pitch temp.

All derived system values are figured with the temp corrected volume. I use BrewCipher, it's all room temp there.
 
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Fly_Guy

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I know my pot is flared, I think my best bet is to do a measure and mark and then compare that to the math.

From there I'll re read this thread and figure out what else I need/want to tinker with
 

Toxxyc

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I do an extra dunk-sparge in a bucket and then suspend the bag by a rope. Let it hang over the kettle for the duration of the boil as well.
 

tracer bullet

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Calculated from observed values. Roughly...

Room temp to strike/mash range: +2.7%
Room temp to boil: +4%
In case others didn't notice, these look like small numbers but are important. On a 5 gallon batch of beer you could be talking 1/8 gallon at mash temp and 1/4 gallon around boil. Meaning this is how much your liquid expands and fools you when you measure it for gravity calculations, deciding if you've boiled enough off, and so on.
 

Fly_Guy

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Does the expansion of water actually 'dilute' or give false readings of gravity?

I took some advanced chemistry classes long ago but a lot of it has escaped me.

To account for those percentages, can one simply multiply those by the inch or mm marking to find out what the corrected reading would be? So for example every gallon is 2 inches, at room temp 5 gallons would measure to 10 inches at a boil, 5 gallons would then measure 10.4 inches?
 

odie

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Does the expansion of water actually 'dilute' or give false readings of gravity?
My hydrometer came with a correction table for temps. FWIW I've been really bad about making sure all my readings are at the same temps. But I've noticed a hot sample will go up several points as it cools off.
 

cmac62

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You know it is funny, I never even thought of squeezing the grain when I was using a cooler MT. Why would I do it now? I recently got an anvil 10.5 and I have done a small sparge in the old cooler MT and full volume, with both I just let the malt pipe sit over the BK and let it drain.

For the grain absorption I remember hearing about 1 gal per 10lb of grain. I'm a little rusty on maths, but I think we are coming pretty close to that with the tests so far. Please correct me if I'm off. :mug:

By the way this thread already has 3x the posts than the like threads below. LOL :rock:
 

tracer bullet

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Meaning this is how much your liquid expands and fools you when you measure it for gravity calculations, deciding if you've boiled enough off, and so on.
I'll expand on that so it isn't confusing. I do the points thing - I don't know if it has a proper name. Let's say I want a 1.050 wort going into my fermenter and I want 5 gallons of it. 50 x 5 = 250, I refer to that as points. So that's my end-of-day target.

After I mash, before I boil, I want to know if what is in my kettle is going to do what I need, or if I need to modify it at all. And let's say I want to have 6 gallons in my kettle after mashing, I know I'll want a gravity for it of 250 / 6 = 42 so 1.042.

If I have "6 gallons" at 1.042, I'm good to go. But there's a catch. This is at mash temps... I need to remember that my kettle should actually show around 6-1/8 gallons, at 1.042. If I actually only see 6 gallons, since it's hot, I know I'm actually a little under target for volume.

Similar for end of boil. Let's say I want 5 gallons, cooled, in my fermenter. If I have 5 gallons in my kettle after boiling, I actually went too far. At boiling temps, the water expansion means I should see about 5-1/4 gallons in the kettle (since, when it cools, it'll just be 5 gallons).

If that made any sense at all.... it is what I mean about thermal expansion of water being important when you measure how much water you have after your mash, and how it relates to how much water you think your grains absorbed.

Does it matter? LOL. Well I have 2 different brew methods so I like to know these things so I can actually replicate a recipe between them. And my job is Process Development Engineer and so it's sort of built in for me to want to know. Not everyone will care.
 

doug293cz

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I'll expand on that so it isn't confusing. I do the points thing - I don't know if it has a proper name. Let's say I want a 1.050 wort going into my fermenter and I want 5 gallons of it. 50 x 5 = 250, I refer to that as points. So that's my end-of-day target.

After I mash, before I boil, I want to know if what is in my kettle is going to do what I need, or if I need to modify it at all. And let's say I want to have 6 gallons in my kettle after mashing, I know I'll want a gravity for it of 250 / 6 = 42 so 1.042.

If I have "6 gallons" at 1.042, I'm good to go. But there's a catch. This is at mash temps... I need to remember that my kettle should actually show around 6-1/8 gallons, at 1.042. If I actually only see 6 gallons, since it's hot, I know I'm actually a little under target for volume.

Similar for end of boil. Let's say I want 5 gallons, cooled, in my fermenter. If I have 5 gallons in my kettle after boiling, I actually went too far. At boiling temps, the water expansion means I should see about 5-1/4 gallons in the kettle (since, when it cools, it'll just be 5 gallons).

If that made any sense at all.... it is what I mean about thermal expansion of water being important when you measure how much water you have after your mash, and how it relates to how much water you think your grains absorbed.

Does it matter? LOL. Well I have 2 different brew methods so I like to know these things so I can actually replicate a recipe between them. And my job is Process Development Engineer and so it's sort of built in for me to want to know. Not everyone will care.
Let's quantify the errors from not doing the thermal expansion corrections in your example:
  • You want 6 gal (referenced to room temp) at 1.042 SG for a total of 250 points pre-boil. If you measure 6.0 gal at 152°F, and hit your 1.042 target (measured at hydro calibration temp), you actually only have 5.89 gal at room temp, and your points are 42 * 5.89 = 247.4 points.
  • At end of boil (~210°F) you measure 5 gal. At room temp this is only 4.80 gal. You started with 247.4 points in your BK, so you now have an OG of 247.4 / 4.80 = 51.5 points or 1.0515.
  • But, to get back to 5 gal (by dilution), the OG becomes 247.4 / 5 = 49.5 points or 1.0495
So, ignoring the thermal expansion corrections will make you come up about a quart short on your post boil target, but if you dilute with water, your OG will still be within measurement error. (Got to admit I was a little surprised by this result.)

I have attached a spreadsheet that shows water density as a function of temperature calculated from two different equations curve fit to measurement data. The two equations give essentially identical results (the difference is less than we can measure with our equipment.) At the bottom of the sheet is a little volume correction calculator. If you put in the measurement temp and measured volume, it calculates the volume at 68°F, and the ratio of the room temp volume to the measured volume.

Brew on :mug:
 

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96Illini

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I'm really interested in hearing from someone who takes accurate pre-boil volume measurements and figures accurate loss-to-grain absorption calcs. So far as I can tell, it's not obvious at all that a squeeze gives significant lautering improvement over an extended (let it hang until ~15m before flameout) gravity-only drain.

*I am not saying squeezing does any harm, I just wonder if it really adds anything worth the effort.

ETA: Speaking towards Doug's point...



That .085 gal/lb is pretty accurate whether I'm brewing my typical ~1.043 batch or an occasional 1.095 for keeping. Give or take a few thousandths of a gallon per pound. Unless I'm trying something new, like that first dry stout with a bunch of flaked barley, my pre-boil volume is very close to my expectations.

So if we assume around .08 gal/lb original grain absorption x 10 lbs of grain for a 5 gallon batch, and further assume we can fairly easily squeeze 1/2 the wort back out, that should be an extra .4 gallons of wort. I guess it really boils down to what the salvaged volume is worth to you. I have been squeezing the bag pretty hard, and if I recall from the last brew session, this figure is pretty close.
 

CascadesBrewer

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I guess it really boils down to what the salvaged volume is worth to you.
Yep! If squeezing that bag for everything it owes gives you satisfaction, go for it! If watching a bag drip for an hour is your thing, then go for it. Half of brewing is just finding a process and equipment that fits your needs and style.

The good thing is nobody has mentioned getting tannins out of squeezing the bag. I think we can put that myth to rest.
 

DBhomebrew

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So if we assume around .08 gal/lb original grain absorption x 10 lbs of grain for a 5 gallon batch, and further assume we can fairly easily squeeze 1/2 the wort back out
That's a bold assumption considering the (small amount of) data collected thus far.

Now we've got...

Gravity only, in a tun or colander:
.1

Gravity only, free-hanging:
.085
.077

On a rack with a little press:
.08

Squeeze the bejeebus:
.08
.075
@96Illini, please report back with your carefully measured numbers from your next batch.
 

gello22

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I hang it then squeeze with gloves. I have adjusted my equipment profile so I have to squeeze some to hit my preboil but not like it owes me money. This gives me some room to hit my volumes. If I come up short I can give it the business and makeup a quarter gallon.
 

96Illini

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That's a bold assumption considering the (small amount of) data collected thus far.
Yea, maybe it's closer to a third? But I am definitely going to do a better job recording the number. And in actual practice, I hang the bag on a pulley above the kettle while I'm heating, put my gloves on, and only give it a couple good squeezes. My mind made me think I gained a fair amount, but we shall see.
 

balrog

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As long as you do the same thing every time, you'll be able to adjust, you'll be able to calculate, you'll be able to repeat. Do what's right for you. Grind the same, process the same, get the same. The times I get in trouble are complete and total brain farts like carefully counting the starting marks in the kettle, incorrectly, and being off exactly a gallon. But since I have "along the way checks" I caught it before the boil.
 

Fly_Guy

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Got a Dremel?

I picked up a pretty cheap SS ruler off Amazon for just this purpose. I measure to the nearest mm which in my kettle works out to the nearest 1.something ounce.

Did your SS ruler come with the cork on the back? I ordered one thinking it would be pure unadulterated SS, to my shame it has the cork. Will that, or the glue that attaches the cork to the SS impart off flavors into beer?
 

DBhomebrew

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Did your SS ruler come with the cork on the back? I ordered one thinking it would be pure unadulterated SS, to my shame it has the cork. Will that, or the glue that attaches the cork to the SS impart off flavors into beer?
Mine's just good old SS.
 

Fly_Guy

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Sweet! My local big box store has one as well that I might just go grab. It's an 18" which should work for my bigger pot (I want to etch this one eventually) as well as being handy for other DIY projects.
 

RM-MN

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All it gives is a bit more sugar. It takes time and my time is limited. I prefer to spend 1.5$ more in grain and not use my effeciency as a proof for my manhood.
It takes time to bring the wort to a boil. I use that time to sparge and squeeze the wort out of the bag. Total time to brew is not affected.
 

MaxStout

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It takes time to bring the wort to a boil. I use that time to sparge and squeeze the wort out of the bag. Total time to brew is not affected.
That's my method (except the sparge part). Hoist the bag over the kettle, fire up the gas. I have 10 or so minutes to kill, so I let it drip dry a while then give it a squeeze.
 

96Illini

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Yea, maybe it's closer to a third? But I am definitely going to do a better job recording the number. And in actual practice, I hang the bag on a pulley above the kettle while I'm heating, put my gloves on, and only give it a couple good squeezes. My mind made me think I gained a fair amount, but we shall see.
After fairly close measurement on my last 10 gallon brew, with 10lbs 4 oz of grain, I recovered a little over 1/3 of a gallon of wort. This is the total recovery from the brew bag AFTER the initial removal from the pot where the bag stops dripping steadily. So after the dripping is essentially complete, and the bag is squeezed hard, I probably saved about 3 net 12 oz beers. Is all that worth it? Only you can decide, but I'll probably keep squeezing the bag pretty hard.
 

beernutz

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I brew 10 gallon BIAB batches usually with 25 lbs of grain in the bag.

I can let the bag hang from a pulley for 30 minutes and still squeeze an additional 1/2 gallon out of it.

No way I'm leaving 4 pints in the bag.
 

GrowleyMonster

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I drain until it is down to the occasional drip, then squeeze. I just wind the hoist rope down around the neck of the bag, squeezing it tighter and tighter, then cross it for another 20 wraps or so going under the bottom, over the top. I get easily another half gallon. Then I hit it with a gallon of boiled water in another kettle, drain and squeeze again, for another gallon of goodness to boil down. Never adds any bitterness that I can detect. for 5 gallons finished beer into the keg I mash 10lb pale 2 row, 1 lb 350 choc, a cannister of quick oats and a cannister of yellow grits at 150f one hour with a half hour cooldown cycle, for reference.
 

Beermeister32

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Then I hit it with a gallon of boiled water in another kettle,
I used some hot boiled water to sparge a BIAB one time and ended up extracting unwanted tannins. What a mistake that was.

I would humbly suggest that rinsing water stay under 170F, in fact I’m using room temperature BIAB rinsing water currently. The cooler water also makes the grain bags easier to handle by cooling the grains.
 
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RM-MN

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I brew 10 gallon BIAB batches usually with 25 lbs of grain in the bag.

I can let the bag hang from a pulley for 30 minutes and still squeeze an additional 1/2 gallon out of it.

No way I'm leaving 4 pints in the bag.
Mill your grains much finer which will raise your mash efficiency, then use less grain to hit your numbers. That should lower the amount of wort left in the bag, maybe all the way down to 3 pints without squeezing. o_O :yes:

I drain until it is down to the occasional drip, then squeeze. I just wind the hoist rope down around the neck of the bag, squeezing it tighter and tighter, then cross it for another 20 wraps or so going under the bottom, over the top. I get easily another half gallon. Then I hit it with a gallon of boiled water in another kettle, drain and squeeze again, for another gallon of goodness to boil down. Never adds any bitterness that I can detect. for 5 gallons finished beer into the keg I mash 10lb pale 2 row, 1 lb 350 choc, a cannister of quick oats and a cannister of yellow grits at 150f one hour with a half hour cooldown cycle, for reference.
There is no noticeable efficiency to be gained from using the hot water and it does come with the risk of extracting tannins if your sparge water is alkaline. It only adds a few minutes to bring the wort to a boil as the hot, wet grains will heat up the room temp or cooler water to a good amount. Save yourself the extra work of boiling the water.
 

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I squeeze, but not too much so that the bag doesn’t crack (it happened to me once).
 

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Since I brew in my enclosed (but far from air tight, with lots of windows) porch, I sunk a big eyebolt into the rafter above where I brew, I hoist up the wilserbrewer bag, fire up the burner, and squeeze out till I get the right volume. I use priceless BIAB calculator, and I hit 81% mash efficiency... plenty good enough for me!

I should buy another bag, just to keep stashed away. But those wilserbrewer bags are durable!
 
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