Mashing overnight ?'s

For you that have done the overnight mash before,
Do you notice any significant bump in efficiency from letting the mash rest so long?
Going to try this on a dubbel that might be pushing the limits on belgian crystal malts,
So I’d like to get the extra fermentability of the long mash.
I average 85% right now, and the predicted O.G. is 1.062, which is about as low as you can go “style” wise,
So a little bump isnt going to hurt anything long as I tweak the IBU’s accordingly. shooting ~20.
You guys mash-in a few degrees warmer to combat the few degrees of temperature loss over 8 hours or so?

Anxious for the news. This process could really reduce brew time. Scott, I can’t see why it wouldn’t work. I suppose hitting it with 170 degree water in the morning to loosen it up and then going to usual processes???

I overnight mash a lot and I don’t see any increase in efficiency by doing it, in fact its the opposite most of the time, although you will get a huge bump in fermentability. I usually mash in high around 154, gets down to mid low 140’s by the morning. If you’re going for a dry, dry beer its a great time saver.

That sounds ideal for what I’m trying to do. Thank you kindly.

Yes, looking forward to this. Finally combining my favorite pastimes, brewing and sleeping one off. :smiley:

I’ve never done it, but when I do extended mash times of 2 hours or so (due to multitasking on brew day, for example), I get a big bump in fermentability, with those beers finishing at 1.008 or even lower. So I would expect a full overnight to do the same.


For the record, I in fact got 0% bump in efficiency,
Hitting 1.062 on 5 1/4 gallons. Mashed for ~10 hours.
So I must be getting good conversion on my 60 minute mashes too.
As they say, we shall see how low it floats.

Did a batch on Saturday, mashed in Friday night, ~9 hours time. Started at 157’ish degrees and ended up at 147. I jumped up 10 points at my post boil reading-1.052 to 1.062. I’m not sure how to compute this jump in efficiency; long mash? Pure luck? Better conversion? All I know is I don’t know. Hoping final gravity will be around 1.015. Doubly hoping the beer will not be dried out.

mash efficiency or brewhouse efficiency?

How dry should we expect? I’m looking to use an overnight mash this weekend to create an american pale ale. Would the overnight mash make it too dry? Is there a style that best fits the body that would result from an overnight mash?

That last overnight mash i did was an IPA mashed at 154, left for about 9 hours overnight, down to the low 140’s by the morning. OG was 1.078, finished at 1.011. Grain bill had 5% sugar and 5% crystal, fermented with US-05. I’d say with an attenuative yeast, 80-85% attenuation is not unusual. Alternative option is to mashout before you turn in for the night, I’ll do this with smaller grain bills where I can get all the volume to fit in the tun. If the grain bill is small enough that i can reasonably mash with 3.5G, then I’ll use 2G of boiling water to mash out before bed, which gets me in the upper 160’s.

Alright, stupid question here. How the heck do you keep the temp in the 140’s over 9 or so hours?
I must be missing something.

I mash in high at 154, and over the course of the night- 9 hours or so- the temp falls from 154 to the low 140’s. I have a tun built from a Coleman Extreme cooler.