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Over night Mashing

Just wondering how many have done the extended mash time. I have not brewed since june due to time constraints. Was hoping to fit in a brew session this weekend but the time table is tight.
I was thinking if i could mash tonight, it woudd cut 2+ hours off of my time for tomorrow.

Have many of you done this?
Thought I could start the mash around 8-9:00 tonight then sparge around 8:00 am tomorrow and begin the boil.

Can I expect good results with this method?

I have never done this, but if I were to do it I would not do a sparge at all. I would dump in all 9-10 gallons and call it a day. Now I kinda want to try this… :slight_smile:

Haven’t done it, but I believe the main issue is holding temperature. A few degrees of loss during a sacc rest is not a big deal, but leaving it for a long time can invite the lactobacillus that is all over the grain to propagate if it drops enough. I bet if you insulated it with a few winter coats or something you would be good.

I have not mashed overnight, but if I did, I would add an extra 3/4 pound of crystal malts or Carapils or lactose because with an overnight mash, the sugars will be broken down by the enzymes a lot more than usual. Your efficiency will also be higher than normal, so you could either skip the sparge, or sparge with far less “enthusiasm” as normal. It’s something I’d like to try sometime. I’m sure it will work great, but there are little tweaks and tricks that would have to be learned through experience, which theoretically would likely include the ones I mentioned here.

I have done it a few times but it has been a while. Works best for beers that you intend to be dry. Or like Dave mentioned you could compensate with more crystal/carapils.

I still sparged because back then i had a small mash tun, but this would do well as a no sparge since youll get a little higher conversion efficiency.

lacto doesnt really get going til the temp gets under 140 and your just doing it overnight it wont be under 140 long enough get sour or funky, if you left it all day sub 140 or something like that id worry about lactobacillus.

Mash thinner or with the total volume of water more thermal mass will keep you closer to your target temp longer, pre heat your mash tun, and add some extra insulation if possible.

Edit: no sparging will also save some time you can fire up you burner while the bk is filling youll be boiling soon after the bk is filled

I use Denny’s batch sparge method

I am planning on brewing a 10 gallon batch of black IPA. I will have to check the recipe when I get home to find the crystal content. how much extra would I want to use???

I like black ipas on the dry side so imo probably not too much more. Kinda depends more on how you want the beer to finish.

Oh yeah, I forgot to comment on Lacto… yeah, it won’t be an issue at all for just overnight. It’s the 24-48-72 hour stuff that will sour the beer a bit. But just for 10 hours? No, no problem at all. I have done a few sour mash beers before, and I can tell you that it definitely takes longer than that to have any detectable impact.

I do it all the time. For something you want dry, just mash in high and let it slowly drop overnight. I usually mash in at 154 or so around 10 pm and get up around 7 or 8 the next morning and the wort is usually still in the high/mid 140’s. It you dont want an overly fermentable wort you’ll have to mash out before you go to bed. The only time I dont overnight mash is when I don’t want a dry beer and dont have enough room in the tun to mash out…great time saver and never had any issues whatsoever with souring wort.

…and I’ve never experienced any differences in efficiency when mashing overnight. Just a more fermentable wort.

I used to do this all the time when my kids were little and free time on the weekends was scarce. Always worked great for me.

Another option is to collect your wort in the brew kettle before you go to bed. Raise the temp to about 180, or even to a boil and then let it sit til morning.

I’ve mashed overnight twice before (on the same recipe). Keeping the mash temperature as high as possible is surprisingly difficult. I use a 10 gallon rubbermaid cooler, wrapped it in a heated blanket set on “high”, and then covered that blanket with two additional blankets.

I started at about 155F, and still lost about 20-25 degrees F over 10-12 hours.

Now you got me thinking…so just to be clear for those of you who have done the overnight Mashing did you “Mash out” at 170 in the morning or just add the over night mash to the kettle and boil?


A mashout is performed to stop enzymatic activity. If you do it in the morning, its useless as the enzymes have run their course. If you’re worried about continued conversion through the night, you’ll either have to do a mashout before bed, or run into your kettle and heat to 170 ish.

I’ve done it once, a 10 gallon batch of Baltic Porter. I mashed in at 11:00 pm ~156 and started the run off at 7:00 am ~142, the mash was very sticky and had a slow run off, the sparge wasn’t much better. After it drained I started another 10 gallon batch with the same grain bill, did a standard rest and sparge, it drained fine. Before I mixed them they both tasted about the same.

I can mash and boil a 20 gallon batch now, so I doubt I’ll try it again, unless I’m doing a 30 or 40 gallon batch.

I do it routinely, start it about 11p-12A, and get up around 6a-7a. Drain the wort, dump in more water at about 170ish to sparge/rinse and all into the boil kettle. It makes the workload seem shorter. I use one of the blue cube type coolers for my mash tun. Most of the time I’ll drop from 153/4 down to about 135 sitting overnight, but by the time the temps drop, the conversion has already taken place. I’ve never had a problem with souring or critters.

I routinely do this, but during the day.
I get my mash ready, about 155*, wrap my 10 gallon igloo with a blanket, and go to work.
6-8 hours later, I come home and only lost about 10* to 145* ish.
boil more water to 180ish to sparge, and I’m good to go.

if anything, my brews taste better! and I like a drier beer, to that’s good too.

it seems like it all takes less time.

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