Author Topic: mash rest  (Read 1952 times)

Offline jtoots

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mash rest
« on: August 25, 2014, 05:34:44 PM »
do you stir during the mash rest?  i haven't been, and i've noticed the following in a couple recent batches:

i'm using a cylindrical cooler for my mash tun.

-i hit my mash temp before closing the lid dead on.
-at the end of the mash i lift the lid and take temp readings in the middle and around the edges.
-around the edges the temp has gone down slightly, as expected (a degree or so).
-in the middle the temp has actually gone UP a couple degrees, as if the heat has migrated into the center of the tun.

any thoughts?  should i adjust my starting temp to account for this?  should i stir once during the rest?  all good, proceed as i have been?

thanks all!

Offline HoosierBrew

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Re: mash rest
« Reply #1 on: August 25, 2014, 05:41:37 PM »
I stir thoroughly, until I get a pretty uniform temp throughout the cooler, then close the lid and leave it alone - the lid doesn't open until it's time to sparge.

EDIT - During the course of the mash, there would likely be some temp stratification throughout the cooler/tun, and temps usually drop a degree F or two, but no worries. A lot of good beer has been made in this fashion by a lot of brewers.
« Last Edit: August 25, 2014, 05:45:58 PM by HoosierBrew »
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Offline erockrph

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Re: mash rest
« Reply #2 on: August 25, 2014, 05:58:13 PM »
I tried stirring a few times. When I stirred I ended up losing about 5 degrees over the course of the mash. No stirring gives me about a 2 degree loss. Needless to say, I stopped stirring.
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Offline jtoots

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Re: mash rest
« Reply #3 on: August 25, 2014, 06:14:18 PM »
Thanks for the replies, gents.  Do you notice the same trend, heat gain in the center of the tun?

I'm thinking that, for example, if I'm aiming for a rest temp of 153, and the center of the tun is at 155-156 by the end of the hour, maybe I should start at 152 to account for this gain.  That said, the edges of the tun drop down to about 151, so the average temp is probably right where I want it and I shouldn't change anything.

Offline HoosierBrew

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Re: mash rest
« Reply #4 on: August 25, 2014, 06:58:30 PM »
..... so the average temp is probably right where I want it and I shouldn't change anything.

That's always been my thought. Don't over think it. Good luck !
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Offline davidgzach

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Re: mash rest
« Reply #5 on: August 25, 2014, 07:39:05 PM »
Thanks for the replies, gents.  Do you notice the same trend, heat gain in the center of the tun?

I'm thinking that, for example, if I'm aiming for a rest temp of 153, and the center of the tun is at 155-156 by the end of the hour, maybe I should start at 152 to account for this gain.  That said, the edges of the tun drop down to about 151, so the average temp is probably right where I want it and I shouldn't change anything.

I've never had heat gain in the middle of the tun.  Are you sure you are mixing thoroughly to start?
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Offline jtoots

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Re: mash rest
« Reply #6 on: August 25, 2014, 07:51:13 PM »
Are you sure you are mixing thoroughly to start?

Yep, I'm sure, and didn't believe it the first batch I saw this.  Strange, right?  I'll be brewing this weekend, looking for it again. 

Offline denny

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Re: mash rest
« Reply #7 on: August 25, 2014, 08:29:18 PM »
Thanks for the replies, gents.  Do you notice the same trend, heat gain in the center of the tun?

I'm thinking that, for example, if I'm aiming for a rest temp of 153, and the center of the tun is at 155-156 by the end of the hour, maybe I should start at 152 to account for this gain.  That said, the edges of the tun drop down to about 151, so the average temp is probably right where I want it and I shouldn't change anything.

How long do you stir when you mash in?
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Offline jtoots

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Re: mash rest
« Reply #8 on: August 26, 2014, 12:21:14 PM »
How long do you stir when you mash in?

I add water first, then add grains a couple pounds at a time, stirring after each addition.  Once all the grain is in and no clumps exist, I use my digital thermometer to get readings in a few locations while stirring to get temp down a couple/few degrees to my target temp.  The flaw I recognize here is that the thermometer isn't reaching down to the bottom of the tun... however, with all this stirring, I don't think stratification would be a major factor (and presumably the top would be the hotter region, and the vertical distance isn't all that significant especially for a 5 gallon batch).  I'd say all in all this takes 5 minutes plus although I've never actually timed myself.  I'll use a timer this weekend.

Offline denny

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Re: mash rest
« Reply #9 on: August 26, 2014, 02:42:25 PM »
How long do you stir when you mash in?

I add water first, then add grains a couple pounds at a time, stirring after each addition.  Once all the grain is in and no clumps exist, I use my digital thermometer to get readings in a few locations while stirring to get temp down a couple/few degrees to my target temp.  The flaw I recognize here is that the thermometer isn't reaching down to the bottom of the tun... however, with all this stirring, I don't think stratification would be a major factor (and presumably the top would be the hotter region, and the vertical distance isn't all that significant especially for a 5 gallon batch).  I'd say all in all this takes 5 minutes plus although I've never actually timed myself.  I'll use a timer this weekend.

Well, it sounds OK, but without being able to read the temp all the way to the bottom I guess you can't know for sure.  Based on what's happened to me before, I'd guess that you don't have heat distributed well enough to begin with.  But that's just a guess.
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Offline Plmac

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Re: mash rest
« Reply #10 on: August 30, 2014, 04:30:16 PM »
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.
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Offline denny

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Re: mash rest
« Reply #11 on: August 30, 2014, 05:34:40 PM »
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.
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Offline hopfenundmalz

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Re: mash rest
« Reply #12 on: August 30, 2014, 05:49:55 PM »
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.


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Offline Plmac

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Re: mash rest
« Reply #13 on: August 30, 2014, 06:43:58 PM »
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.


Many do it that way. Easy, it is.

Totally agree, I was just thinking if his mash tun was holding heat like a heat sink it could raise the temp.  I guess the real question, Is your beer coming out the way you expect it to?  To sweet?  Mouth feel? Final Gravity as low as you expected?  Mash temp to High?
If it aint broke, don't fix it.

Offline klickitat jim

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Re: mash rest
« Reply #14 on: August 30, 2014, 08:07:16 PM »
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.

If it took me several years to preheat my tun, I would try to find a better way too.