slate fermenter

[brocko492]

I came across some pieces of rather thin slate approx 1/2" thick that was cut into relatiely manageable size pieces 18" X 24", the price was right as my brother is a stone mason and can easilly cut smaller if needed. I was thinking of trying to make a slate fermenter out of it. My concept in my head would be to build a framework out of lumber and support the slate to it , probably with liquid nails or something similar (obviously external). The joints could then be sealed with food grade silicone or even with masonry I suppose. As long as it doesn't leak it would work. Sort of like an aquarium tank, but a hell of a lot heavier! I have a sheet of aluminum I can put over the top of the framework and seal down with a gasket and bolt through the frame system. Who knows maybe even pitch a ton of yeast and try an open process.

Question is does anyone know the process used by the old european (predominently English) breweries to clean and season the slate? I know several of those are hundreds of years old and the food to microorganism ratio is so in favor of yeast that it really is unique to every brewery. But I imagine that every now and again they need to break in a new one. Would they just scrub the stone with a mild acid cleaner and then season with a wort perhaps??

 

[scinerd3000]

i had never heard of this before and did some searching. From what it seems, they develop there own yeast colonies somewhat like an infected barrel for lambics. On samuel smith's website:Samuel Smith's Old Brewery, they talk about how they are "open" containers again with no top similar to a true lambic. Everything i found is uncovered containers. You would ideally need the wooden "ribs" you were talking about to hold the immense weight and pressure when they are full. I definitely want to see how this comes out. Please post pictures!!!

 

[Cold_Steel]

I read about using slate for a fermenter. The weight is what i didnt like about the idea.

 

[Boerderij_Kabouter]

BYO had an article two years ago about building a stone fermenter with tiles....


[off to dig]

 

[Displaced MassHole]

BYO had an article two years ago about building a stone fermenter with tiles....


[off to dig]

I was just remembering that one.......not sure of the month/year though.

 

[Cold_Steel]

http://farm4.static.flickr.com/3022/2678244752_fbea76782a.jpg?v=0

I found the image of one.
So how would one join them together, morter?

 

[brocko492]

Definately going to check out the BYO article and see what they recommend for sealing the joints. Like I say my brother is a stone mason so he probably has all the necessary fabrication tools. I did a bit of research into this and found a very old book on google called "Principles and Practice of Brewing" by WJ Sykes...it is a public domain book because it was printed in 1897...wow! Anyway this is a seemingly pretty cool concept as far as fermenting in these Yorkshire squares, it is actually a chamber over a chamber (jacketed with a water tank for maintaining temperature) with a covered trough/ manhole in the center that contained the yeast and could be covered and used for repitching. The process apparently was to flow part of the wort into the top chamber and start the fermentation (essentially a huge starter as only 1-12lbs per barrel was used in each inital pitch). Once it got going the entire wort could then be added and all was allowed to go into the lower chamber. As fermentation happened the yeast rises to the top through the manhole they could recirculate the beer back on the yeast that bubbled over fell into the trough a couple times (apparently they weren't too concerned about oxidation). Essentially the process roused the yeast, ala shaking the carboy of a high gravity beer. Eventually yeast that collects in the trough is separated from the beer, much like a conical concept but inverted.

I just have to figure out a scaled down version of this for the typical batch size I do of about 12 gal . I think it would be pretty simple to construct the manhole/ trough with a 4" pipe inside a 6" pipe and cap. The organ pipes could probably just be 1/2 copper waterline.

For sure the whole thing has to be framed in for structural integrity, but that is the easy part really. I may a well put somekind of a stand and casters under it too...lot of weight.

To the drawing board I go.

 

[leboeuf]

I just pulled up that book.... it's epic

quote: "hopback..... may be constructed of wood or iron"

 

[brocko492]

Yes an epic for sure...obviously there is a lot of out dated info there and more modern ways of doing things, but its fun to look at the old school methods too. Reality is the whole of the process of brewing ales is not all that much different than it was then.

 

[Brewers Hardware]

Sounds like a very interesting project.

Is the idea that you don't sanitize it but rather let it develop a natural flora and fauna or do you try to sanitize it between batches?

The reason I ask is while the slate would be difficult enough to sanitize, grout would be impossible and you'd want to use some sort of silicone in the seams I'd think. Grout also wouldn't allow any flex in expansion and contraction when you fill and drain the thing, which would crack for sure. Of course, Dow Corning didn't make silicone back then so I wonder what they used in the seams...

 

[brocko492]

I believe the idea is to let the yeast grow in the trough under cover and then put a portion of the wort into the top vessel and get it going, like a really big starter, before pitching the remainder of the wort. The idea is not to encourage contamination, even today nothing is sterile, we are just trying to minimize risk.

He does describe how the squares were cleaned and sanitized in those days, i would probably use an iodophor solution sanitizer...obviously the slate is porous so it has to be a no rinse product. We are in 2009 not 1897, and I am not much for mixing chemicals.

For homebrewing purposes, I would probably just make a large starter a day or two in advance and place it into the trough and flow my wort from my chiller over it when the starter came to krausen. Recap the trough/ manhole between batches for subsequent repitchings. Then the squares could be hot water rinsed and re iodophored.

The idea is that there would be some natural "flora and fauna" like you say but that would give the ale its own unique flavor. The worst of the airborne contaminants were never really an issue because you have so many yeast cells in the top vessel and they'd be at high krausen. I have removed the lid off the primary several times and as long as the fermentation is at that point the krasuen and the CO2 rising from it is a natural deterrant to bacteria. Obviously this assumes that there is no pathway on which things can enter your fermentor, a dusty environment, kids, pets, for example.

The vast majority of the worlds beer styles have at some point been openly fermented, even pilsners

Good point on the flexion forces on the joints. They must have allowed for expansion and contraction some how...further research required.