Double Mash

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insane_rosenberg

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Last night I was reading through "Radical Brewing" by Mosher, and came across something interesting. An 'old fashioned' method of producing strong beers.

As Randy says:
"The process is straightforward. A mash is made as for a normal beer, then the runoff wort, instead of being boiled, is heated to strike temperature and then used as the liquor for a second mash..."

Now I have a couple of high gravity brews in the pipeline, and was worrying I'd have to bulk them up with extract as I could never mash that much grain in my urn. Now I find there is a way!

So the plan...
- Have my LHBS split my grain bill in two batches
- BIAB mash one batch as usual
- Lift out and squeeze
- Pour in sqeezed liquor and top up to original volume
- Empty and rinse bag, while urn gets back up to stike temp
- Retun bag to urn and add second batch of grain
- Continue on my happpy way to high gravity beer

I did a quick search and couldn't find any threads on this topic. Is anyone doing it already? Can anyone see any reason that i'd be wasting 7kg + of grain and 3 hours of my life?

Before ya start... <_<
There is currently no milk in the fridge and I can't afford any at the moment. Hence, no I am not going to to 3V right now.
 
Great idea, in saying that I have no idea if there would be any issues.

I'm a fellow budget and space restricted BIAB brewer, if this was true might just stay with BIAB in the long run :beerbang:

I wait with interest!!
 
No reason to ever go 3v - several entries in the current Nationals being judged tomorrow are proof (may Allah be all seeing and guide the judges well) and beer is more cleansing that milk :icon_cheers:

However the main problem I can see with doing a BIAB double mash with higher gravity is that you are going to end up with a lot of goodies locked up in the spent grains compared to 3v. Mosher would be assuming that the grains in batch #1 would have been sparged. I would personally hoist the bag out and do a side sparge in a bucket with #1, using a few kettles of 75 degree water, add those runnings back into the first batch of wort and use that wort as strike liquor on the second batch of grain. You might even get an opportunity to do a further sparge in a bucket with #2 if it's not going to make it too weak. Play it by ear. :icon_cheers:

How big is your pot? I regularly do 6 + in a 40L but if you are smaller then a double mash should be quite feasable.
 
You would imagine the second batch would need to be rinsed well as the wort will be very thick and if the grain is absorbing wort it'll be absorbing twice as much sugar as usual.
 
Thanks guys, good feedback about the rinsing. It's not something I've done with BIAB so far (all two batches).

Bribie, I too have a 40L urn. I'm just a bit worried about the efficiency dropping with large quantities of grain. Not sure if it's a valid fear. It has also just occured to me that I may struggle to lift 8.3kg (dry weight) of grain from my urn, as I have nowhere to rig up a pulley system. I could also sqeeze more efficiently two 4kg grain bags than one 8kg one, given that the final wort will be equally thick for each method.

The high gravity brews were meant to be two months or so off... I may have to adjust the schedule :icon_cheers:
 
With a 40L urn I'd cram it to the top with the first mash and squeeze well on lifting, maybe use just 45 percent of the grain in the first mash and don't sparge on the side. Then do the second mash and side-sparge that one, and do an extended boil up to two hours if it looks like you've over done the sparging. The reason you don't want to do a sparge with the first mash is that you could end up with too much wort and get a spillover when you dough in the second lot. As Mark says the real trick is to get as much fermentables out of #2 as possible so side sparge that one. I reckon you won't have any trouble, go for it.

To give you room to manoevre, plan to put in the bittering addition after half an hour of boiling then after the first full hour do a hydro check to see how the gravity is going and just keep boiling till you hit your preferred gravity (cooling the sample of course):icon_cheers: So worst case scenario is that the bittering will be in for an hour and a half but I do that quite often anyway.
 
Google "reiterated mashing" Thirsty Boy has mentioned it a couple of times; you will get squilions of hits, more than enough to keep you entertained.

It's an interesting process, tho not without its drawbacks, you are trading off a lot of efficiency.

The advantage 3V over full volume mashing is that you can recover most of the extract fairly easily. Just do a fairly heavy mash, collect the first runnings, then sparge into a second container. Basically this is how beer was made before sparging was invented, what was called a triple mash (really a triple batch sparge not a mash) yielding Strong Beer from the first runnings, Table Beer - from the second runnings, Small Beer from the third.

I reckon if you think it through you should be able to come up with a fairly straight forward process that yields a Big Beer and a hefty Mild to Standard beer maybe do two mashes and get two pretty much full volume beers.

MHB
 
Thanks for the terminology update MHB. Always a trap when searching (brewing seems even worse than the web in general).

Further reading seems to confirm it does work, just have to adjust my estimated efficiency. Which I'm happy to do, at least it gets me around my not-physically-possible situation outlined above.

I'll be sure to post the results once I've given it a shot!
 
I'm typing without thinking here but could you do the side sparge Bribie suggested & use that to top up for evaporation during the boil? Might be a worthwhile idea depending on what volume & abv you want. Or it may not be.
 
If you're worried about the amount of tasty stuff left behind in the bag after the second mash, you could always set it aside and use it for a partigyle.

After you've boiled and removed the wort from the urn, refill the urn with water, heat to strike temperature and return the "spent" grain, with some extra fresh grain (I've no idea how much without doing research, but I think Mosher has some info), and do a lawnmower beer.

T.
 
Awesome! I'm going to do this this arvo.

EDIT: will write everything down and get back with numbers.
 
I'm just a bit worried about the efficiency dropping with large quantities of grain. Not sure if it's a valid fear. It has also just occured to me that I may struggle to lift 8.3kg (dry weight) of grain from my urn, as I have nowhere to rig up a pulley system.

Yep... as the grain bill size goes up the efficiency goes down... well at least that was my experience for BIAB that is.

When i used to BIAB i did double batches and the comfortable number for me was to use between 9-10kg of grain in a 50L keggle. I could still get around 70% efficiency. But that was with a mashout, squeeze and dunk sparging in an esky, before adding all the liquor back to the kettle

Lifting out this grain wasn't too hard, worst thing for me was getting over the lid of the keggle, but as an urn brewer you'll have no probs.

I'm interested in this method, i'll be keen to hear of anyone doing it and what any potential drawbacks may be.

NickJD... assume you're going to employ this today... definitely report back.

:icon_cheers:
 
NickJD... assume you're going to employ this today... definitely report back.

Will do. Hope this is cool with Shane - more the merrier I hope.

I think it'll suit my crappy technique nicely.
 
One point to think about might be the temperature of the malt thats in the bag you just lifted out. If you havent done a mashout there will still be enzyme activity going on you could end up with very dry beer.

MHB
 
One point to think about might be the temperature of the malt that's in the bag you just lifted out. If you haven't done a mashout there will still be enzyme activity going on you could end up with very dry beer.

MHB

MAsh out! Thems tecnikle talking.

I'm like, hoist bag, squeeze like buggery into bucket, chuck grain, add bucket to kettle, bring to strike, add bag and second grain bill...
 
It seems unlikely that no mashout would be a problem. In a big beer the problem is more likely to be under attenuation, not over attenuation, surely!

T.
 
It seems unlikely that no mashout would be a problem. In a big beer the problem is more likely to be under attenuation, not over attenuation, surely!

T.

Could always bring the first mash's liquor to 78C and then let it come back to strike ... then do the second mash if concerned?
 
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