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Old 01-15-2013, 08:01 PM   #1
Dec 2012
Posts: 8

To give you full picture of my questions, I'll write few words of background.

Normally I brew all-grain in electric kettle with braid filter fitted to the kettle. During mash-in and mash-out a grain bed forms on lower parts of the kettle covering braid filter. When it comes to filtration, grain bed stops all particles and gives high clarity of liquor.

When I read about BIAB I found it so interesting I thought I'd give it a try. All parts about mash-in and mash-out went as good as they normally do, but I got concerned little bit after. When I pulled the bag out of the kettle liquor was far from clear and looked more or less like mud. Braid filter was all sticked with small particles forming mud. I had to put my bag with malted grains again into the liquor to create a grain bed, as what happens in my normal brewing method, and clean my filter - then i got usual clarity level.

It all was quite of exhausting, but finally I think I must had done something wrong about BIABing, so here are my questions:

1. Should liquor after pulling bag out be muddy? If not, what did I miss that it happened?
2. Do you use mechanical stirrer or stir with wooden brewing spoon?
3. My bag has a bottom with little holes, their diameter is about 3 mm (0,3 cm) - are they too big (that is how it looked when i bought it, nothing was modified)? Should i get/make a new bag?

If you have any questions that could possibly make me close to solve that problem, feel free to ask.

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Old 01-15-2013, 08:16 PM   #2
Nov 2010
Solway, MN
Posts: 10,242
Liked 1943 Times on 1541 Posts

Is your desire to have clear wort (liquor) or is it to have clear beer. The bag you use should be a fine mesh, no holes in it. When you pull the bag from the kettle the liquid will often be cloudy. No problem, it clears out when the fermentation is done and the beer clears in the fermenter and even more so in the bottles.

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Old 01-15-2013, 08:22 PM   #3
jwalk4's Avatar
Jun 2012
London, Ontario
Posts: 954
Liked 163 Times on 132 Posts

If I understood your post correctly, you're wondering if your wort is unclear because of the BIAB process? In a word, yes, that is what is to be expected. You will have 'muddier' wort because, at least in the purest sense, BIAB doesn't require vorlaufing (the process of filtering wort by recirculation over the grain bed). I'm not saying that vorlaufing is impossible with BIAB, but is not essential to the process.

I have BIAB'd and use a large spoon.

BIAB doesn't have a standardized bag unfortunately, but a 5 gallon paint strainer bag or a fine mesh voile cloth are common.

Hope that helped.
Fermenter 1 - Vienna /Saaz SMaSH
Fermenter 2 - Dry as a bone
Drinking - various craft brews, Tiny Bottom PA
Beer styles I'm trying to nail down: APA, Porter, Mild, Amber, & Something Yellow and Fizzy.

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Old 01-15-2013, 08:44 PM   #4
Dec 2012
Posts: 8

Thank you both RM-MN and jwalk4.

According to what you both have written, I should get a new bag or modify the one I have now.

Also, I would like to know, how could I increase clarity level of my BIABed liquor. Filtering via braid filter doesn't work due to lack of grain bed, but using another vessel and trying to filter through bag doesn't seem to look well.

Below you can see pictures of my bag, left side of each picture shows bottom, right - side. I'm wondering if side part is good enough and should make give my bag second bottom using voile. What do you think of that idea?

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Old 01-15-2013, 08:55 PM   #5
Feb 2011
Yorba Linda, CA
Posts: 916
Liked 46 Times on 38 Posts

Voil fabric works really well. You can pick up voil curtains from kohls for under 10 bucks and sew it into several bags. There is really no worry with the clarity. Mine is ”muddy” also, but after the boil and chill it becomes add clear as can be.

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Old 01-15-2013, 08:57 PM   #6
Fennis's Avatar
Apr 2011
Readfield, Maine
Posts: 385
Liked 26 Times on 19 Posts

I've done many BIAB batches and while its been cloudy, its never been muddy. The bag I use is much finer than the one you have in a closeup photo. Here is an example of what I typically use:

Its not the best photo, but its much finer than the picture you have displayed.

As said above, I've actually ended up using a paint straining bag most of the time now as its cheap and disposable. Still, if you let the beer sit in the primary for a little while longer, and maybe use whirlfloc or irish moss, you will have a clear beer.

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Old 01-15-2013, 09:01 PM   #7
Aug 2012
minneapolis, minnesota
Posts: 1,488
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I'd get something different. Those holes look pretty big. Either a brewing specific one a paint strainer bag from a hardware store or the voil curtains if you can sew or have someone that can.

Don't freak out about clarity. It will work itself out in the end although it can be disturbing at first.
I hate Walder Frey...

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Old 01-15-2013, 09:38 PM   #8
Dec 2012
Posts: 8

BryceL, Fennis, inhousebrew, thanks for your responses. My bag was bought in a brewing store and was made probably in Germany and thats weird they make bags that are not fine enough. Question is, does paint straining bag or any other "industrial" bag oxidize during mashing and contaminate liquor?

Also, I might get some of that kind of material:

What do you think about it? It's quite common on my university and probably somebody would share a piece with me.

And again, do you think I should make/buy whole new bag or just add second bottom to this one I already own?

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Old 01-15-2013, 10:28 PM   #9
Jan 2013
Posts: 9

I've brewed 19 batches using BIAB so far. My experience has been that wort is cloudier than that resulting from a traditional lauter process. Clarity is never an issue in the finished beer provided I use whirlfloc and cold crash.

The bigger issue is hop utilization. My half-baked hypothesis is that the additional cloudiness is from protein, and the higher protein levels lead to lower hop utilization than would result from a traditionally lautered beer of the same gravity. Research suggests that hop utilization is a function of protein levels, and the reason higher gravity beers have lower utilization is because higher gravity = more protein. Stands to reason, then, that higher protein for a given gravity would lead to lower utilization than would be expected at that gravity.

My clone attempts are consistent with this hypothesis. I'm hitting all my mash targets but simply not getting the utilization I want and can't predict my results effectively. To that end, I'm in the process of moving away from BIAB and to a traditional mash/lauter tun.

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Old 01-16-2013, 09:35 AM   #10
Dec 2012
Posts: 8

skibikejunkie, solution may be to keep your wort in 53C for about 30 minutes just before heating during mashing. This lets peptidases "crack" long protein particles into short ones, what has stright connection with clarity of the beer and hop utilization. Shorter particles don't float and sink on the bottom of your kettle, what should reduce protein amount and increase beer clarity. Don't know how it's commonly called in english, but translating form my language it should be "protein break".

To sum up whole topic, this all made me think of such strategy to get less cloudier beer:

1. Do protein break before heating up to 65C.
2. Boil longer than usual to make small particles fall on the bottom of the kettle.
3. Use whirlfloc/irish moss during boiling or/and gelatine in secondary.

Do you have something to add?

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