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Author Topic: overnight mash in an Igloo-type cooler?  (Read 856 times)

Online ScallyWag

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overnight mash in an Igloo-type cooler?
« on: November 23, 2023, 11:13:52 am »
Has anyone here done overnight mashes in an Igloo-style cooler?  If so, how much does the temperature drop in, say, 8 or 10 hours? 

My 5gallon orange Igloo generally holds the heat well when I am doing a 90-minute mash, I think I've done almost 2 hours a time or two.  I can cover it in blankets to give it some extra insulation.

I'm just a little nervous about getting a sour mash or other contamination...  I hate to risk sacrificing an entire batch that might become a dumper.

Also, if the mash involves quite a bit of Rauch malts, do I risk making the Igloo taking on the odor long-term/permanently?  Maybe a Rauchbier recipe isn't the best one to test this out on.

TIA for any advice/critique.

Offline redrocker652002

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Re: overnight mash in an Igloo-type cooler?
« Reply #1 on: November 23, 2023, 11:32:09 am »
Not much to add except that my 10 gallon Igloo would never be able to hold that much heat for that long.  I have not tried it yet, but in test runs with just water I have trouble keeping it at 150ish for the 60 minutes I need for a normal mash let alone that long.  No idea what it would do to the wort, but just putting in my two cents worth, and believe me, that's about all it's worth. 

Offline denny

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Re: overnight mash in an Igloo-type cooler?
« Reply #2 on: November 23, 2023, 11:49:40 am »
Not much to add except that my 10 gallon Igloo would never be able to hold that much heat for that long.  I have not tried it yet, but in test runs with just water I have trouble keeping it at 150ish for the 60 minutes I need for a normal mash let alone that long.  No idea what it would do to the wort, but just putting in my two cents worth, and believe me, that's about all it's worth.

Water doesn't have the thermal mass a mash does, so will lose heat faster.
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Offline denny

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Re: overnight mash in an Igloo-type cooler?
« Reply #3 on: November 23, 2023, 11:51:18 am »
Has anyone here done overnight mashes in an Igloo-style cooler?  If so, how much does the temperature drop in, say, 8 or 10 hours? 

My 5gallon orange Igloo generally holds the heat well when I am doing a 90-minute mash, I think I've done almost 2 hours a time or two.  I can cover it in blankets to give it some extra insulation.

I'm just a little nervous about getting a sour mash or other contamination...  I hate to risk sacrificing an entire batch that might become a dumper.

Also, if the mash involves quite a bit of Rauch malts, do I risk making the Igloo taking on the odor long-term/permanently?  Maybe a Rauchbier recipe isn't the best one to test this out on.

TIA for any advice/critique.

I haven't done it in a round cooler, but I have in a rectangular. Lost maybe 5-8 F overnight. Wrap it 8n a blanket or towels and you should be fine.
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Online ScallyWag

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Re: overnight mash in an Igloo-type cooler?
« Reply #4 on: November 23, 2023, 12:23:07 pm »
Thanks guys.  I can definitely live with losing 8-10 degrees, I think.  At what temp do I need to worry?  Maybe I will mash a bit higher than I usually do.

ETA:  by the way, I will probably test this tonight, if I do I will report the temperature specs back so others can have that data point.

redrocker652002, do you preheat?  I typically put ~160 degree water in my cooler first, about half full for 30-60 minutes before I start mashing, to get it to 'warm up'.  It drops a bit but stabilizes.  After initial mash-in and stir, I usually add a tiny bit more water to adjust, but it never drops more than about 2 degrees over the first hour, and maybe 3 or 4 degrees total when I've mashed out at 90-100 minutes.  And that's always without any blankets or towels for additional insulation.

Denny's right about the grains being a stabilizer (thermal mass), you may want to try your hour-long test with a thick mash and see what you get.  Is your 10gallon a rectangular cooler, or is it the orange cylinder?  Mine is the orange cylinder, maybe there's a difference in the insulation levels/materials.


Online pv

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Re: overnight mash in an Igloo-type cooler?
« Reply #5 on: November 23, 2023, 02:24:29 pm »
I have a 7 gal round igloo-type cooler that I have mashed overnight with a couple of times.  I have always wrapped them in moving blankets.  From my target mash temp measured before I seal it up to about 10 hours later, I believe that I have not lost more 10 degrees.  No idea about the smoke smell lingering in the cooler.  I think you'll be in good shape.
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Online ScallyWag

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Re: overnight mash in an Igloo-type cooler?
« Reply #6 on: November 24, 2023, 10:41:05 am »
Well I didn't do the overnight mash (yet), as I broke my finger rough-housing with my massive dog.  Right before brewday too, dammit.  >:(

It's surprising how much you cannot do with a middle finger in a splint, and it's just too much hassle (and pain) to lift & carry anything.

I am going to try the overnight mash next month though, once I have 2 good hands.

Offline denny

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Re: overnight mash in an Igloo-type cooler?
« Reply #7 on: November 24, 2023, 10:48:20 am »
Heal well and quickly!
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Offline fredthecat

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Re: overnight mash in an Igloo-type cooler?
« Reply #8 on: November 24, 2023, 01:15:30 pm »
hi, i was trying this as a method to break up.my brewday time
. i did it on a bunch of batches with mixed success. the wort pH will drop, in some instances. it will also tend to make a very dry beer, i got high 80%s, like 88% attenuation at the higheat i think with lager yeasts in allmalt worts.

i had good results with mashes from 2 to 4 hours, ie. leaving it alone for an afternoon. when i came back i believe the temp was still in the 130s or so in a pre-warmed igloo cooler.

try it, but yeah it may result in unexpected results. i chose to stop doing it.

Offline majorvices

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Re: overnight mash in an Igloo-type cooler?
« Reply #9 on: December 01, 2023, 05:57:21 am »
Ever smell a mash that's been left overnight in a cooler? It usually has a bit of a lactic twang to it. I have done overnight mashes in my oven with the oven set at 170 degrees and that worked well.

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Re: overnight mash in an Igloo-type cooler?
« Reply #10 on: December 01, 2023, 08:30:06 am »
I have done extended mashes (2-3+ hours) a couple times in my Anvil Foundry set at 150F or so, but never a full overnight, except when I once made a Berliner Weisse with some grain as the lacto agent (after regular mash, I brought up to near boil then pitched some grain and left it overnight until I reached my intended pH).
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Offline denny

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Re: overnight mash in an Igloo-type cooler?
« Reply #11 on: December 01, 2023, 08:54:10 am »
Ever smell a mash that's been left overnight in a cooler? It usually has a bit of a lactic twang to it. I have done overnight mashes in my oven with the oven set at 170 degrees and that worked well.

Can't say that I've noticed that, but I've only done it a few times
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Offline erockrph

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Re: overnight mash in an Igloo-type cooler?
« Reply #12 on: December 01, 2023, 10:53:35 am »
Ever smell a mash that's been left overnight in a cooler? It usually has a bit of a lactic twang to it. I have done overnight mashes in my oven with the oven set at 170 degrees and that worked well.

This is what kept me from ever experimenting with an overnight mash. Depending on your temps and how well your mash tun holds them, this sounds dangerously close to a kettle sour process to me, or at least close enough to keep me away.
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Offline denny

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Re: overnight mash in an Igloo-type cooler?
« Reply #13 on: December 01, 2023, 11:15:22 am »
Ever smell a mash that's been left overnight in a cooler? It usually has a bit of a lactic twang to it. I have done overnight mashes in my oven with the oven set at 170 degrees and that worked well.

This is what kept me from ever experimenting with an overnight mash. Depending on your temps and how well your mash tun holds them, this sounds dangerously close to a kettle sour process to me, or at least close enough to keep me away.

I would recommend you try it and decide for yourself.
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Offline majorvices

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Re: overnight mash in an Igloo-type cooler?
« Reply #14 on: December 01, 2023, 02:41:16 pm »
Ever smell a mash that's been left overnight in a cooler? It usually has a bit of a lactic twang to it. I have done overnight mashes in my oven with the oven set at 170 degrees and that worked well.

Can't say that I've noticed that, but I've only done it a few times

If it only dropped 5-10 degrees like you said in your post them you wouldn't develop lactic. Just depends how long and how much temp. the cooler loses.