Home Brew Forums > How do you split up the grain bill for a partial mash.

04-29-2009, 09:55 PM   #1
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 How do you split up the grain bill for a partial mash.

I'd like to try a PM for the first time and I would like to convert BierMuncher's Nierra Sevada Pale Ale recipe.

For a 5 Gal batch the AG bill looks like this:

7.5# 2-Row
.5# Carapils
.5# Crystal 60

I've got 2 row and Pale LME, how do I determine how much of each for a partial mash?

thanks

04-29-2009, 11:07 PM   #2
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First determine how much total grain you're able to mash (counting the carapils and 60L), then convert the remainder of the 2-row to extract using a 1 to 0.75 ratio. For instance, if you're shooting for a 4 lb partial mash, I'd use:

.5# Carapils
.5# Crystal 60L
3.0# 2-row

The remaining 4.5 lbs of 2-row converts to 3.38 lbs (3 lbs 6 oz) of pale LME (4.5 X 0.75 = 3.38). That assumes a 65-70% efficiency in the mash. If you do a batch or two this way and your OG ends up a little low, you can compensate in the future by either using a bit more grain or a bit more extract.

FYI, if you use dry malt extract you use a 1 to 0.60 conversion factor.
1 lb grain = .75 lbs LME = .6 lbs DME

It's also important to figure out your mash and sparge water volumes based on the size of your boil pot. I usually do my partial mashes using a ratio of 1.3 quarts per pound of grain, figure out that total volume and subtract it from the size of my boil pot. That will be my sparge volume (up to 2X the mash volume, and I usually add about half a quart for grain absorption). I hope that makes sense...

Good luck!

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Last edited by ifishsum; 04-29-2009 at 11:14 PM.

04-29-2009, 11:26 PM   #3
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Quote:
 Originally Posted by ifishsum First determine how much total grain you're able to mash (counting the carapils and 60L), then convert the remainder of the 2-row to extract using a 1 to 0.75 ratio. For instance, if you're shooting for a 4 lb partial mash, I'd use: .5# Carapils .5# Crystal 60L 3.0# 2-row The remaining 4.5 lbs of 2-row converts to 3.38 lbs (3 lbs 6 oz) of pale LME (4.5 X 0.75 = 3.38). That assumes a 65-70% efficiency in the mash. If you do a batch or two this way and your OG ends up a little low, you can compensate in the future by either using a bit more grain or a bit more extract. FYI, if you use dry malt extract you use a 1 to 0.60 conversion factor. 1 lb grain = .75 lbs LME = .6 lbs DME It's also important to figure out your mash and sparge water volumes based on the size of your boil pot. I usually do my partial mashes using a ratio of 1.3 quarts per pound of grain, figure out that total volume and subtract it from the size of my boil pot. That will be my sparge volume (up to 2X the mash volume, and I usually add about half a quart for grain absorption). I hope that makes sense... Good luck!
Thanks for answering my first question re: how to figure out the grain bill AND answering my next one about how much water I use for mash vol and sparge volume.

I have a 16 qt brew pot on hand. To prevent boil over I can probably top out at 14, maybe 15 quarts boil volume.

If I did a 4 lb grain bill of 3# 2-row, .5# Carapils, .5# Crystal 60 I would need 5.2 quarts mash volume at your 1.3water/lb of grain.

That leaves me with 8.8 quarts for sparge volume? 9.3 to account for grain absorption.

Do I top up with water in my carboy to reach 5G, just like I would with an extract batch?

I guess I could be asking these questions in Deathbrewer's thread but i appreciate the answers here.

04-29-2009, 11:35 PM   #4
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I guess I'm psychic

Sounds like you have it down on the water volume, and you should get good efficiency with the bigger sparge, I can barely sparge more than my mash volume because my brew pot size. You could easily drop a quart off the sparge to give you more room in your pot. And yes, I'll top it off in the fermenter with water up to recipe size. I usually buy spring water in the gallon jugs and put them in the freezer when I start brewing, so they help my wort cool down to pitching temperature faster. The water is usually just below freezing temp after 3 hours or so. Another plus to topping up is that you can check your gravity before you add all the water, and add just enough to reach your target OG. Just be sure to stir well to get a correct reading.

Another thing I like to do is wait until the last 10 minutes or so left in the boil to add the extract, starting the boil with only the mash and sparge runnings. It helps keep the color lighter, and also lets me use the original hops schedule without compensating for a partial (concentrated) boil. This method has worked out great for me.
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Last edited by ifishsum; 04-29-2009 at 11:42 PM.

04-30-2009, 12:07 AM   #5
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Quote:
 Originally Posted by ifishsum Another plus to topping up is that you can check your gravity before you add all the water, and add just enough to reach your target OG.
do you have a calculation for this or do you just add some water, take a reading and adjust as you go? ie add more water if you need to get lower

and ya, I was going to do a late extract addition. I've been doing that more and more and is certainly recommended in DB's thread.

04-30-2009, 01:50 AM   #6
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No calculations there, I usually end up with 2.5 gallons after boiling down so I anticipate up to 3 gallons of water. I'll start with 2.5 gallons (I usually make 5.5g batches), mix it well and check the gravity. If it's where it's supposed to be, I leave it there - but if it's a couple of points high (it usually is) then I add the other half gallon of water before sealing the fermenter.
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04-30-2009, 05:17 AM   #7
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ifishsum thanks for all your tips.

I've got another thought. If i have a 16 qt brew pot and i am mashing 4 lbs of grain and using only a little over 5 quarts of water will I have trouble maintaining mash temps? I've read that a key to keeping it around 152,3,4 is to have your mashing pot as full as you can get it.

Do you experience a drop in mash temps or is your brew pot pretty full?

04-30-2009, 07:22 AM   #8
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I solved that problem by doing the mash in a 2 gallon round beverage cooler (using the grain bag). If preheated with hot tap water first, it doesn't usually lose more than a couple of degrees over an hour. I use the boil pot to heat the mash water and then the sparge water, after the mash I move the grain bag directly into the boil pot for the sparge. Once the bag is removed and drained, I pour the mash runnings from the cooler into the boil pot and fire it up.

Either way you should be mashing another vessel besides your boil pot. If using an uninsulated pan it will hold temp better with more water and grain. You can add another pound of 2-row if you want, just reduce the LME by 3/4 pound. Remember to adjust your mash and sparge volume if you do that.

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