# Double Mash



## insane_rosenberg (27/10/10)

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.


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## beerdrinkingbob (27/10/10)

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!!


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## Bribie G (27/10/10)

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.


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## MarkBastard (27/10/10)

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.


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## insane_rosenberg (27/10/10)

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:


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## Bribie G (27/10/10)

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.


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## MHB (27/10/10)

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


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## insane_rosenberg (27/10/10)

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!


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## Hatchy (28/10/10)

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.


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## drtomc (28/10/10)

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.


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## Nick JD (28/10/10)

Awesome! I'm going to do this this arvo.

EDIT: will write everything down and get back with numbers.


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## argon (28/10/10)

Shane R said:


> 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:


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## Nick JD (28/10/10)

argon said:


> 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.


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## MHB (28/10/10)

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


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## Nick JD (28/10/10)

MHB said:


> 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...


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## drtomc (28/10/10)

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.


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## Jye (28/10/10)

Here is the previous thread for you to read. Linky


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## Nick JD (28/10/10)

drtomc said:


> 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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## drtomc (28/10/10)

Absolutely. Me? I wouldn't be concerned.


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## Nick JD (28/10/10)

drtomc said:


> Absolutely. Me? I wouldn't be concerned.



Neither. I've got mash #1 on at the moment.


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## Thirsty Boy (28/10/10)

I'd start with a much more "normal" l:g ratio. Think about your sparges. I'd be aiming for 1 sparge of the first grist, and 2 spurges of the second grist. So you need 4 separate quantities of water. Remember also, that although you will have a normal volume in your pot, you have used an abnormally large amount of grain... So you will have more trub than usual etc.

The way to do it, is to initially plan the brew as though you had a much bigger pot and you were going to do it all at once in there. So calculate water, losses, trub - as if it were all one big arsed batch, then split your volumes to give you what you want.

For instance: say you wanted to start your boil with 38L (you are planning to boil down to your final volume, even though that might take 2 hours)

So given say 10kg of grain, and losing 0.5 L/kg... You will need a total of 48L.

You'll have to mash with at least 22L for 10kg of grain - which leaves you with 26L to use as sparge. And I would be inclined to split that up into 10L to sparge the first grist once & 2 sparges of 8L each for the second grist.

Of course, because you will need a long boil anyway....you can always sparge with more than that and keep it aside to add to the boil as it progresses. Doing that will allow you to mash with a little more water too if you want.

The more your sparge, the more efficient it will be, but the longer the boil will need to be to get down to volume. Eventually you get to the ultimate level of pointlessness, where you could simply have done two separate 5kg mashes, boiled them down to half volume and combined the two worts in the fermenter.

So somewhere in between is a "reasonable" compromise between extract efficiency and time efficiency.. You'll have to decide where it is.

Cheers

TB

Edit - spelling and PS

PS - remember, you don't need to mash the first grist for very long. As long as it's properly hydrated and the starch has been given a chance to gelatinize and dissolve... You are good to stop. You aren't bringing anything to the boil, the enzymes are all still there, they will keep working for the duration of both mashes. If anything, better because you are adding a fresh batch of new enzymes part way through. 15, 20 minutes and get that thing out of there, get your new one in and start sparging the first one, it might be a little starchy... But when you add it back to the mash... The enzymes in there will fix it up. Let your second mash complete properly though. I would mash out the second one to help with efficiency (direct heat, so no need for infusion water) the first one doesn't need it because once again, you will be recombining it's run-off with an enzymatically active second mash anyway.


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## Nick JD (28/10/10)

I just mashed 3kg of BB pale and 100g of caraaroma and got 15L of 1.051 (had to top back up to 15L and the boiling water brought it almost straight back up to strike). 

No sparging, and there was still quite a bit of sugaz in the grain, but I had to get the bag empty - two bags FTW! 

Dumped in another 3kg of malt at 70C strike and that's mashing now. It'll be interesting to see if I get to 1.100... 

It's probably going to be some sort of strong lager (~1.065 SG) with buckets of Nelson and Cascade in it - but I'll have to work out volumes when I get the 15L SG. Will know about 4:30.


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## Crunched (28/10/10)

Watching this..


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## MarkBastard (28/10/10)

Crunched said:


> Watching this..



Yeah me too.

In fact, oddly enough this could end up being a way to get more out of stove top brews. I mean it certainly takes longer, which sucks, but if this was to be combined with what I read in an earlier thread about the mash not needing to be 60 minutes if you mash higher, maybe you could pump out a double mash in 60 minutes?


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## Nick JD (28/10/10)

Mark^Bastard said:


> Yeah me too.
> 
> In fact, oddly enough this could end up being a way to get more out of stove top brews. I mean it certainly takes longer, which sucks, but if this was to be combined with what I read in an earlier thread about the mash not needing to be 60 minutes if you mash higher, maybe you could pump out a double mash in 60 minutes?



I dare say you could quite easily.

Though what I'm seeing is the second mash is not as masharific (technical term) as the first.

After sparging with 4L of water somewhere between 70 and 80C - which I saw was completely needed with all those sugaz - I've now got 16L of 1.087, which is 15L of 1.092. Still pretty respectable (and the bag is still running quite high, so I might get another point or two from it).

So something is happening in the second mash to reduce the efficiency a tad, or there's simply more sugaz left in the grain.

Still - getting 30L of 1.046 from a 19L pot? Heh heh heh. Funny stuff! Me like this technique.

Just calculating my hops now. I think I'll make 20L of 1.069 strong lager with 35 IBUs, half of them from < 20 minute additions.

So 12g of Nelson for 60, 8g for 20 - and 12g of NZ Cascade for 20 as well will get me 35 IBUs.

Gotta love making shit up as you go.


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## insane_rosenberg (28/10/10)

Nick JD said:


> Will do. Hope this is cool with Shane - more the merrier I hope.
> 
> I think it'll suit my crappy technique nicely.



Be my guest Nick! After all that's why I started the topic, to see if anyone had actually done this! And now someone has. 

I'm not as big on "making shit up as you go". So some indicative efficiency values (from the real process) will be great. Plus hopefully it tastes alright too!


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## Nick JD (28/10/10)

Shane R said:


> Be my guest Nick! After all that's why I started the topic, to see if anyone had actually done this! And now someone has.
> 
> I'm not as big on "making shit up as you go". So some indicative efficiency values (from the real process) will be great. Plus hopefully it tastes alright too!



Cool. I think the guys have already done this on that other thread linked to up above.

I had to wait for some numbers on the hydrometer before I could work out any hop stuff and in that way I was brewing on the fly. 

There will probably be some taste effects from the overgravity boil - but I suspect these could be seen as good, or bad depending on the style.

A 7% lager with Nelson and Cascade sounds ripper to me, but. And the "extra hour" is not really anything but waiting - there's only really 15 minutes of extra effort.

I'm sold. Thanks, Shane!


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## Nick JD (28/10/10)

Do I need to add double the whirlfloc?


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## Nick JD (28/10/10)

Nick JD said:


> Do I need to add double the whirlfloc?



Too late - I used 2x just in case. There must be more break in there.


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## felten (28/10/10)

I would use the same amount of whirfloc, its based on your kettle volume not gravity right?

too late now though ;P


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## bradsbrew (28/10/10)

Nick JD said:


> Do I need to add double the whirlfloc?



Hmmmmmmmm, thats a good question. Should the whirflock be calculated by volume of wort or grain used/trub? 

Cheers


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## Nick JD (28/10/10)

bradsbrew said:


> Hmmmmmmmm, thats a good question. Should the whirflock be calculated by volume of wort or grain used/trub?
> 
> Cheers



I assumed grain bill. I've hassled all the Geeks - and WHERE ARE THEY NOW I NEED THEM!


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## manticle (28/10/10)

I've never adjusted my whirlfloc due to gravity. I would assume volume but I'm happy to be wrong.

Never read or heard anything that suggests whirlfoc amounts should be gravity dependent.

Geeks helped you in the past Nick. Look at your current stovetop method - worked out by geeks.


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## bradsbrew (28/10/10)

Nick JD said:


> I assumed grain bill. I've hassled all the Geeks - and WHERE ARE THEY NOW I NEED THEM!



ANHC


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## bradsbrew (28/10/10)

manticle said:


> I've never adjusted my whirlfloc due to gravity. I would assume volume but I'm happy to be wrong.


Same her Manticle I have never adjusted due to high gravity but all my high gravity beers have been black so I have not had any issues with clarity. I do make sure I keep the ratio corect for volume though, no matter what style of beer.


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## manticle (28/10/10)

No issues with clarity in the finished product either but you're still trying to leave hot break behind no? 

The fact that whirlfoc is operating on removing proteins makes me think that sugar levels are less important than volume of wort. Someone who knows can hopefully steer us in one or another direction but most instructions suggest x tab per y litres regardless of wort gravity. Obviously we all know nstructions can be lacking.


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## Nick JD (28/10/10)

manticle said:


> ...worked out by geeks.



...Perfected by morons.


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## MHB (28/10/10)

manticle said:


> No issues with clarity in the finished product either but you're still trying to leave hot break behind no?
> 
> The fact that whirlfoc is operating on removing proteins makes me think that sugar levels are less important than volume of wort. Someone who knows can hopefully steer us in one or another direction but most instructions suggest x tab per y litres regardless of wort gravity. Obviously we all know nstructions can be lacking.



The sugars and the protein are both extracted from the grain, logically as you extract more of one you would extract more of the other.

MHB


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## manticle (28/10/10)

So what's the relationship between whirlfloc amounts and gravity? I know that adding too much whirlfloc can work against the effectiveness so if there's a linear relationship, it's worth knowing. Say an average 20 L final vol of 1050 is 1/2 tab, what's a 20 L 1100 barley wine need?


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## Nick JD (28/10/10)

manticle said:


> So what's the relationship between whirlfloc amounts and gravity? I know that adding too much whirlfloc can work against the effectiveness so if there's a linear relationship, it's worth knowing. Say an average 20 L final vol of 1050 is 1/2 tab, what's a 20 L 1100 barley wine need?



A healthy liver?


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## MHB (28/10/10)

Whirlflock is Carrageenan and Dispersant (the part that makes it Whirl- not just flock) so when people weigh one that's worth remembering, I always use a 1 whole tablet in ~25 L wort. Good rule of thumb would be if you doubled the gravity to double the dose.

That said its really far too complicated to be precise (not just for home brewers) all advised doses come with a caveat to determine exact doses by in house trials, fine if you're doing the same beer over and over again.

This is a very worthwhile read View attachment 41737
and there is some very good stuff here at the IBD (the wort boiling sections are relevant).

MHB


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## manticle (28/10/10)

Thanks for the links. Will make interesting reading when I'm less tired. Skim read the first but need to come back to it. Second looks chock full of goodies.


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## felten (29/10/10)

I found this part interesting "As collagen possesses a high degree of structural order, it is temperature sensitive and is denatured at moderate temperatures into gelatine which has little or no fining activity."


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## MHB (29/10/10)

And every time I post that crap from the supermarket isn't the same as real finings, I'm a retarded money grubbing retailer bastard, trying to make you pay extra. So I won't say that.

Mark


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## Bribie G (29/10/10)

Next time I bottle I'll do a couple of clear PETs with and without some gelatine, take some photos and lets see how the cow sits in the cabbage patch 

Yee har.

Actually I found isinglass to be very effective but a bitch to store and prepare and smells like cat food treats.


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## Nick JD (29/10/10)

My double mash batch of strong lager (20L) is now in the fermenting fridge at 12C with two packs of S189 and no almost headroom, so a cleanup is probably in order tomorrow or the next day when the Krausen Monster from the Deep awakens. 

I'm going to bottle half of it as is and dilute with deoxygenated water the other half to 4.5% alc - I'd like to see how it holds up taste-wise doing commercial-style high grav stuff.

What are the possible flavour changes associated with high grav? Any pitfalls I should be aware of?


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## MHB (30/10/10)

MHB said:


> And every time I post that crap from the supermarket isn't the same as real finings, I'm a retarded money grubbing retailer bastard, trying to make you pay extra. So I won't say that.
> 
> Mark




Just don't get you at all, can't contribute jack to the forum, except maybe - Ohhh look at me look at me aren't I great; I can hang a ball in a keg - like that's hasn't been done a dozen times before.
FYI there has been a discussion going on regarding the relative merits of every imaginable fining for as long as I have been a member. Probably a lot longer, a bit of self deprecating humour regarding a long held and often stated opinion and you have to jump in make it personal.
Tempting as is it to get into a slanging match I'll just leave it at; you know yourself better than anyone else does and chose a very appropriate name!
MHB


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## Bribie G (30/10/10)

MHB, thread wandering way off course, so whatever....... in view of the reported huge success people have with gelatine finings - which of course have their downside as well such as 'fluffy bottoms' when added at bottling stage that negates most of their usefulness in that particular instance - are you saying that gelatine as such is not an effective fining agent? I see that that PDF, which is good reading, is really 'unsourced' and I wonder why they say that gelatine has little fining effect when so many brewers would differ vehemently. 
Of course I can't imagine CUB backing up a gelatine truck to the brewery but at our scale of brewing it's always worked just fine (oops pun) for me, and that's why I'll do a side by side with a gelatined bottle when I bottle off next week, with photos. 

Cheers


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## manticle (30/10/10)

BribieG said:


> that's why I'll do a side by side with a gelatined bottle when I bottle off next week, with photos.
> 
> Cheers



I was interested in having a go at something similar. It was a homebrew shop owner who told me not to buy the finings and just use gelatine instead and to the best of my knowledge they seem to work. However I also CC and leave brews in secondary for a bit so clarity could come from elsewhere. I've had clear beers just with CC.

I'd be interested in fining one glass with quality HB finings (probably from grain and grape), 1 with davis or similar and 1 with nothing and seeing what difference if any, I can see. I realise it's not a foolproof scientific investigation but it will help to satisfy my curiosity.


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## Nick JD (30/10/10)

Sometimes gelatine works too well and I have almost no yeast in the bottles. 

I'm _not _a retarded money grubbing retailer bastard, trying to make you pay extra.


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## MHB (31/10/10)

Exactly my point Sometimes there are lots of different gelatines some work as finings some dont, I wouldnt choose a yeast that might work, or a malt that might be well modified, same in this case.

Mark


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## Kai (31/10/10)

I always found that the good old Davis Gelatine works better than no finings at all. That's racking warm beer onto a solution in the secondary then throwing it in the fridge.

These days I go for fish guts, when I remember to use finings. Making some hazy beer lately so need to start fining again


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## insane_rosenberg (31/10/10)

Don't mean to be the thread Nazi but...

:icon_offtopic: :icon_offtopic: :icon_offtopic: :icon_offtopic:
I thought this was the Double Mash thread not the relative-merits-of-various-finings-sold-at-LHBS-or-elsewhere thread.


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## felten (31/10/10)

Welcome to the forums.


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## Nick JD (31/10/10)

My 45 Double D mash is tasting like mother's milk!


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## insane_rosenberg (31/10/10)

I'll be interested to see what FG you get down to. High FG was one of the things I was worried about if I had to use a big pile of extract.


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## Nick JD (1/11/10)

Shane R said:


> I'll be interested to see what FG you get down to. High FG was one of the things I was worried about if I had to use a big pile of extract.



I'm not usually too worried about FGs but I'll measure it for you if you'd like when it gets there.


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## insane_rosenberg (1/11/10)

I had a feeling you might say that Nick! Don't worry about it mate, I'm going to give it a try regardless.


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## insane_rosenberg (13/2/11)

Cracking this method out today for my strong Belgian ale. Will report exact process and results this evening.


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## darryl (10/5/12)

Sorry about bringing up an old topic. I was just wondering what kind of success people are having with this method. I am using a 40l urn for biab as well and want to get the most out of the system without really relying on adding DME. I have tried pushing it with about 7.1kg of grain to 32l of water, but that pretty much blew me efficiency to about 58% (into fermenter).


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## Mayor of Mildura (10/5/12)

Hi darryl

I've tried this method and it works OK. I made a barley wine with a 10kg grist split into 2. 

My preferred method though with large grists is to do a more of a 2v type thing. Mash in with the whole grist and half the water. Then drain into a bucket or pot and batch sparge with the remaining volume to get to your pre boil volume. Hoist bag and combine runnings and boil away. 

Advantage of double mash is you only have to lift half amount of grist at a time, only need one pot. Disadvantage takes longer and lower efficiency. 

Cheers


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## stux (10/5/12)

darryl said:


> Sorry about bringing up an old topic. I was just wondering what kind of success people are having with this method. I am using a 40l urn for biab as well and want to get the most out of the system without really relying on adding DME. I have tried pushing it with about 7.1kg of grain to 32l of water, but that pretty much blew me efficiency to about 58% (into fermenter).



A good dunk sparge will go a long way to improving your efficiency on the big grain bills


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## Mayor of Mildura (10/5/12)

Stux said:


> A good dunk sparge will go a long way to improving your efficiency on the big grain bills


I guess what I was suggesting Stux was a "reverse dunk sparge" (I reckon I have invented a new brewing term :lol: ) . Saves having to lift, carry around and poke into a bucket 10kg + of wet grain. Many ways to skin a cat i guess.


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