Has anyone split their brew session into two different days? I was thinking about doing a BIAB mash in the evening, and then the next morning completing the boil process.  
The benefit to me is breaking a 5 hour session into a manageable 2 hour evening session, and then a 3 hour brewing session the next day.
Any issues with taking this approach?

I have split, but not that way. I often mash and boil, then pitch the yeast the next day after the wort has cooled. This works well for me.

But, I think you can find discussions about succesful overnight mashing.

Until you reach a boil to kill off any nasties, you still have a very high potential for nasties (define that however you wish) in your wort. I wouldn't recommend it. They will chew on that wort overnight.

Having said that... I did it once myself with good results. After collecting the preboil volume in my brew kettle, I put it in my chest freezer set for the mid 30's. Any bugs in there would have been very slow to do anything to the wort... kind of like putting leftovers in the fridge instead of letting the sit on the counter. It took forever and a day to get 6.5-ish gallons to a boil from that temp on the stove top.

I did read somewhere to bring the wort up to 180 degrees to pasteurize it... Before letting it sit overnight. But I'm still not sure if I want to try it.

I've seen some talk on this subject on HBT. There are a few advocates of this style over there if I am not mistaken.
I'd make doubly sure the mash tun was thoroughly sanitized and then report back to us your findings and observations.
Don't we always quote "Mr Beer, My Beer, My Way ? "

I've got to agree with Banjoman. If you wanna do it, do it.


That seems reasonable.
The thing you want to avoid is anything that would lead to a sour mash when you don't want one.
Sanitizing some of the preboil equipment and pasteurising the wort seems reasonable to me.

Exactly. Lacto lives naturally on the surface of grains, right? Unpasteurized wort will sour. I just don't know how soon.

yeah, sounds about right, prof and pudge... they were just talking about sour mashing on a recent episode of the sunday session (either the one with black star co-op or the one with tide brewing/trophy fire, i think)... once the mash (or the wort, in this case) sours there's no going back. but i think sour mashing happens around 115° F. so then the question i have is... if vat pasteurization occurs at 145° F for 30 mins, why would the runnings (which have been holding above 145° F for an hour) not be pasteurized? when the wort drops below 145° F when it's sitting there cooling, that would be when the bugs come to party... but, i have no idea... just playing devil's advocate.

The time between mashing in the evening and brewing in the morning is not that long. I think Lagerpmp might be okay with no modifications to his process. However, changing the time between mash and boil is already a modification. So, is anything required to compensate? I think just reasonable steps.

8 hours or so? might not be a enough time to start to sour, but who knows. i don't know. but, i would think so long as a tight fitting lid is on, it'd be fine. nasties can't climb... just hitch rides on specks of dust.

As noted in my "sour mash" link above, "Keep the mash in a sealed container and hold it between 95 and 120° F for two to four days."

Of course that's for best results with the wanted bacteria. There is a bit about avoiding unwanted bacteria and it involves killing it with higher temps. 2-4 days is quite a bit less than 8 hours.

EDIT: I am approaching this question backwards. DON'T do what is required to have a sour mash.

I think I will reserve this method for a future brew session. Tomorrow I have time to do both the mash and boil. But I will definitely try the split brew session in the near future and report how it turns out.

Thanks Professor... That's helpful. Otherwise I might have left it at 100 degrees overnight, and gotten some sourness. Sounds like I'll need to keep it warmer, or colder than the "sour" temp range to avoid that.

Yeah, if you pasteurise (to kill stuff) then do a cool down to 70 or so you should be fine (covered) overnight.

This would be a helluva chance for an experiment. Boil half same day and save the other for a next day boil.

+1... one day... heh

Well, I did the split session. Mashed last night and then cooled the wort down to 75 degrees and put in my fridge overnight. Six hours later I pulled it out and did my boil/brew session. 2 hours last night and 3 hours this morning. Will see how this turns out.

The recipe was a Patersbier with an OG of 1.050

I hope it works perfect. That would be a handy method if pressed for time.

same here. be sure to update us.

I saw your plans and decided to do the same thing (partial mash), but when I got the grains out, I decided to make dog biscuits. So while I was waiting, I thought I'd bring the wort to a boil and just do half of the boil then and the other half today. Then I decided I'd been at it that long, why not just keep going. So I ended up going to bed around 3.

But I'm interested in how this works also because I think it's likely that I'll do it at some point if it works for you.

I'd love to hear how this comes out.
And if it does I would suggest that you contact James at Basic Brewing Radio and see if they would do a show on a Split Brewing Session.

Yep, I hope the beer turns out great. I'd like to do this method as an alternative when needed.

I'll keep you all posted, especially in about 3 weeks when it's time to keg it. That will be the taste test.

I may modify your idea for my Hefe. Everyone loved it last year and I have enough supplies on hand to make 9 finished gallons. I can only boil enough for a five gallon batch.
I may mash, split, boil half same day, and the other half the next day. If I attempt I'll keep everyone posted.
Thanks for the idea!

"Time" is exactly why I'm thinking of moving to extract for a while. I love all grain brewing, but there are times I feel a little rushed trying to get a 5-6 hour brew in or I have a very small window of opportunity during the week (usually early Sunday morning) to get a brew session in.

This method would make things easier.

Yeah, Pudge, time is why I'll probably be sticking with extracts for the foreseeable future. I can manage an hour a lot easier than I can manage a chunk of a few hours or more.

I just wanted to followup on this and let everyone know that the finished product was very good. I just kicked the keg a few days ago and the Patersbier was a very good brew. So, I don't see any issues with doing the split session brewing. I would do this method again, if pressed for time.

I did a similar thing on my barley wine, but kept it on low heat on the stove overnight. Worked out great so far!