# Biab Mash Thickness



## Bribie G (7/1/11)

There seems to be a couple of schools of thought, 3V brewers enquiring and posting quite often about optimal mash thickness, and at the other extreme BIAB brewers saying "oh yes, we regularly do 6:1 liquor to grain ratio and it turns out just fine. 

However this bloody thing just keeps niggling me: as I posted before Xmas I bought a dedicated plate and thick bottomed stockpot and I've decided today to:







Mash with 20L in the urn to around 6 kg of grain (an APA)
Heat 10L in my dedicated stocky to boiling, and use that for an instant mashout, pump well and drain baggie. With my setup it's a simple exercise, I hadn't done it before because it's a fair drag from the kitchen to the brewhouse. 

That's going to give a liquor to grain ratio of around 3:1 which is still a bit sloppy but interested to see if it affects efficiency etc. Unfortunately I haven't been measuring efficiency, hopefully I'll get a fairly good idea when I measure the OG on pitching compared to previous brews with similar grain bill. If it doesn't make any difference I won't do it again, but gotta try everything once  

Apart from efficiency does anyone know any other benefits of a thicker / thinner L:G ratio? German brewers use hot liquor to adjust temperature doing a stepped Hochkurz mash (Zwickel may have info on this) so their mash thickness changes during the process as well. 

:icon_cheers:


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## argon (7/1/11)

Bribie... while not strictly answering your query... Make sure you have a couple more litres on hand in the stockpot to bring your main mash to mashout temp. 

6kg of grain in 20L of 66C (assumed mash temp) plus 10L of boiling water (i always calculate boiling infusions as 93C) brings temps to 74.4C. 

Assume you want to get to 76-80C for mashout. If you were to add 14L of 93C (boiling) you would bring 66C to 76.5C for a mashout.

So i would prepare a touch more water than 10L... might as well fill up the stock pot and add water and stir while monitoring temps to bring to mashout. 
The beauty of the urn i guess is you can add a little heat too if you don't quite make it.

Hope it turns out well. I've been stuck by this before... so just passing on my vast experience in learning from my fecking things up :blink:


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## Bribie G (7/1/11)

Thanks Argon, I'll have a couple of extra jugs ready as well and cut the mash strike volume down to maybe 18. 
It also occurs to me that by having the mashout liqour on the boil while the BIAB is finishing its mash I'll probably tweak an extra 20 mins of faffing about raising and lowering and raising the bag while the urn would normally be heating from mash to mashout. :icon_cheers:


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## argon (7/1/11)

BribieG said:


> Thanks Argon, I'll have a couple of extra jugs ready as well and cut the mash strike volume down to maybe 18.
> It also occurs to me that by having the mashout liqour on the boil while the BIAB is finishing its mash I'll probably tweak an extra 20 mins of faffing about raising and lowering and raising the bag while the urn would normally be heating from mash to mashout. :icon_cheers:



No worries... that's exactly why i like infusion mashouts... it saves some time... virtually instantaneous temp rise. If you have the capacity to have the water ready, then why not? Careful though... you're adding an extra vessel to your BIAB... the pitchforks will come out! h34r: or will they be put away?... i dunno :blink:


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## RdeVjun (7/1/11)

BribieG, that's actually similar numerically to the Maxi-BIAB method which seldom gives <75% efficiency, often well >80%. For L:G, Maxi-BIAB (link below) uses about 3:1 and at least one sparge of about 1:1, but I lean towards 2:1. The extra water only enters the figuring at pitching, that's at post- boil dilution and it allows OG target to be reached perfectly every time (at the expense of variable volume of course). 
After many dozens of batches of this method I've been mindful of the similarities to more conventional mashing, but I don't have much doubt that BIAB is suited to the higher- gravity mashes (or lower L:G ratio, which ever way you want to look at it) provided there's a sparge step; making it a combined sparge/ mashout is possible too, I am not convinced it is that much more efficient but it is easy to effect anyway.
That's the efficiency side, I couldn't say if this mashing method has any particular advantages with respect to other characteristics such as flavour, but most seem to have been fairly well accepted so far... :chug: B)


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## pb unleaded (7/1/11)

What are those "rocket launchers" in the picture?


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## Bribie G (7/1/11)

Also due to my streamlined and almost perfectly ergonomic setup here (definitely more luck than good management  ) the double brew stand is on wheels and I can 


Do mashout as planned but don't squeeze bag to buggery as I normally do
move brewstand along and position bag over the nappy bucket sitting next to urn under skyhook
Lower and do a sparge in the bucket with extra liquor
Raise and drain 
meanwhile bringing main wort to the boil.
boil second runnings in stockpot to save heating time in main urn. 
Recombine runnings
boil for 90 instead of 60 to bring the wort back to what it would have been. I've got a mark on the sight tube for 23L cube or 20L cube.

:beerbang: 

Car's in for a service all day so I'm stuck home anyway (Bertie is in the Bike hospital <_< ) so time for some fancy footwork.

Edit: RO water system from Gryphon Brewing.


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## Bribie G (7/1/11)

Hey RdeV - embarrassing question but erm:

For a 3:1 ratio and 5.7 kg grain bill, what strike liquor temperature should I go for?

B)


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## BjornJ (7/1/11)

not knowing the temp you are going for, I'm guessing for 65 degrees just to have something to use:

5.7 kg of grains in 3:1 ratio with water is 17.1 litres of water.

Guessing your grains are 23 degrees.

Beersmith then says you need to heat the water to 71.5 degrees to hit 65 degree mash temp.

(also assuming your 4 kg Birko urn)





thanks
Bjorn


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## Florian (7/1/11)

Bribie, just a word of warning that comes from experience. With that extra vessel you are also adding another possible safety hazard to your brewery. Call me an idiot but I have once managed to spill 15 liters of (fortunately 'only') 80C water over my feet while trying to lift the pot over my mash tun. I quickly pulled my shoes and socks off and jump straight into the cold pool and stayed there for an hour. Still, the blister took about six weeks to heal and the scar is still highly visible. The beer still turned out alright though. 

So just make sure those extension cords of yours are out of the way


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## eamonnfoley (7/1/11)

You can easily mash at 4:1 (and maybe lower, but I havent tried) with BIAB and get decent effciency. This is more preferable if you have alkaline water because using a high (6-7) L:G ratio pushes up the mash PH considerably. Just add top up water before you pull out the bag, so the liquid lost to grain is of a lower gravity - hence improving efficiency.

Check out Braukaiser's site for more info on mash thickness with relation to german brewing. And PH related matters. He did an experiment on PH and mash thickness.


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## Thirsty Boy (7/1/11)

Umm - not to be too negative about it. But what is it you are attempting to work out? That a 3:1 LG ratio works? I dont think that there is any doubt about that at all - it does.

Remember, BIAB uses high L:G ratios, simply and only because it allows the method to be a "1 pot" solution, not because it works any better or any other esoteric reason. High because it had to be high to meet the requirements of the technique; and the fact that it works quite so well was a surprise to all concerned.

3:1 and a sparge.... You are just doing a "normal" mash rather than the unarguably abnormal mash that is standard BIAB.

If you are just having a go because you want to have a go at something you've never done - fair enough. But do remember, that what you are doing when you drop the L:G ratio to that level is not something different or unusual, its actually normalising your process. So i wouldn't gasp too loudly in surprise when it works perfectly well.

Mash thickness can effect the fermentability of your beer - but not by a lot given you are only changing from very thin to just thin. If you were going from BIAB to say 2.1:1 it might be something you needed to take into consideration. You might also find that because your enzymes are more concentrated and they are less liable to denaturing via heat in a thick mash - that you would be able to deal with a higher load of unmalted adjunct before you bumped into conversion issues.

Go back and look at the first 15 or so pages of the main BIAB thread - all the arguments about thin vs thick mashes were had several times over in there. The way it actually happens though... Is that it makes bugger all difference. Flirting with the edges rather than anything fundamental.

TB


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