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Old 02-22-2008, 01:15 PM   #1
alex_r
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Default Cleaning stainless conicals

From a previous post, I mentioned that the first batch of beer I brewed and fermented in a new stainless conical had a strong metallic taste. Through some assistance from others more knowledgeable than myself, the current theory is that I didn't allow the surface of the conical to oxidize after the cleaning. This is supported here http://www.carolinabrewmasters.com/e...Offflavors.htm where it says...

Metallic
The undesirable metallic off-flavor is produced by certain chemicals that are harsh & unpleasant akin to the aroma & taste of a rusty nail, & may make beer undrinkable in extreme cases. Other metallic descriptions include tinny, coinlike, & bloodlike. Primary control metallic off-flavors would be to eliminate all sources of contact with beer & iron/aluminum surfaces, such as unplated mild steel, aluminum & cast iron. Look for high iron concentrations in brewing water (example: Clackamas County, Oregon) & treat or replace accordingly. Furthermore, cleaning stainless steel or copper without passivating (oxidizing the surfaces to form a protective layer of oxide on the metal) can also cause this, especially with new equipment. Lastly, use quality malt products & store them in correct containers under proper conditions.

So my question is now, what do you consider the best way to clean this in the future to assure that the surface properly oxidizes and I don't have this metallic flavor again? Some things I have read say to use a Scotchgaurd pad and clean with PBW. Then towel dry, let it sit for a week, and sanitize prior to usage. Does anyone agree or disagree with this approach.

Thanks!

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Old 02-22-2008, 01:29 PM   #2
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All taken from John Palmer's How to Brew.... Go buy the book NOW!

http://www.howtobrew.com/appendices/appendixB-1.html


Stainless steel is stainless because of the protective chromium oxides on the surface. If those oxides are removed by scouring, or by reaction with bleach, then the iron in the steel is exposed and can be rusted. Stainless steel is also vulnerable to contamination by plain carbon steel, the kind found in tools, food cans, and steel wool. This non-stainless steel tends to rub off on the surface (due to iron-to-iron affinity), and readily rusts. Once rust has breached the chromium oxides, the iron in the stainless steel can also rust. Fixing this condition calls for re-passivation.

Passivating stainless steel is normally accomplished in industry by dipping the part in a bath of nitric acid. Nitric acid dissolves any free iron or other contaminants from the surface, which cleans the metal, and it re-oxidizes the chromium; all in about 20 minutes. But you don't need a nitric acid bath to passivate. The key is to clean the stainless steel to bare metal. Once the metal is clean (and dry), the oxygen in the atmosphere will form the protective chromium oxides. The steel will be every bit as passivated as that which was dipped in acid. The only catch is that it takes longer-- about a week or two.

To passivate stainless steel at home without using a nitric acid bath, you need to clean the surface of all dirt, oils and oxides. The best way to do this is to use an oxalic acid based cleanser like those mentioned above, and a non-metallic green scrubby pad. Don't use steel wool, or any metal pad, even stainless steel, because this will actually promote rust. Scour the surface thoroughly and then rinse and dry it with a towel. Leave it alone for a week or two and it will re-passivate itself. You should not have to do this procedure more than once, but it can be repeated as often as necessary.

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Old 02-22-2008, 02:06 PM   #3
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Default Thanks, Donasay!

I, in fact, do have Palmer's book. That is where I saw to clean it with the green scouring pad and dry it. The instructions for the conical actually say to use a cleaner such as PBW, then let it dry. That's why I was wondering what the general consensus is as far as what to use to properly oxidize the surface.

Thanks for the input!

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Old 02-22-2008, 02:24 PM   #4
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OK I'm a bit confused, I had to miss something.

The Problem: Your first batch in the new SS Con has a metallic taste.

The Cause: The SS is not properly oxidized.

The Solution: Without access too nitric acid, allow the metal exposure to air and it will oxidize naturally.

So did they ship this thing cased in grease like a engine block or something? Seems like the time it sat in storage and on a shipping truck would have exceeded any time need to naturally oxidize. I need to re-read I guess.

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Old 02-22-2008, 02:29 PM   #5
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Essentially he scrubbed the thing so hard he took the oxidation layer off of it and then didn't let it sit for long enough to build the layer back up.

He probably either scrubbed it with something harsh like steel wool or used a harsh chemical that took the top layer off, then put beer right in it without letting it sit a week.

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Old 02-22-2008, 02:32 PM   #6
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Cool, simple explanation. I hope to get one of these soon, so this really sparked my interest.

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Old 02-22-2008, 02:49 PM   #7
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I simply clean mine with water and iodophor (recommended by blichmann engineering). I also tear apart the fittings after every brew and soak them as well.

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Old 02-22-2008, 03:06 PM   #8
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Quote:
Originally Posted by Donasay


To passivate stainless steel at home without using a nitric acid bath, you need to clean the surface of all dirt, oils and oxides. The best way to do this is to use an oxalic acid based cleanser like those mentioned above, and a non-metallic green scrubby pad. .

Oxalic acid base cleaner = Bar Keeper's Friend

non-metallic green scrubby pad = Scotch Brite ( the blue pads are better less abrasive they won't scratch the stainless steel.
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Old 02-22-2008, 03:51 PM   #9
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Default My previous post.

Here's my previous post regarding the cleaning regiment. Right now, I'm not totally sure the cleaning of the conical is what caused it or it's just coincidence that an infection happened with my first batch in the conical. Here's how I cleaned it.

"We did what I thought was a thorough cleaning of the conical with the same. 30 min soak with the PBW, 10 min or so with the SaniClean, and several minutes contact with the StarSan." I only lightly scrubbed with a non-abrasive sponge to distribute the cleaning and sanitizing solution.

Like I said, I'm not sure it was the conical, I'm just wanting to make absolutely certain for next time.

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Old 05-30-2008, 06:10 AM   #10
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I think I love cleaning/sanitizing with bleach. I rinse extremely well with near scorching water. Never had an infection or medicinal flavor. For my kettle, chiller and spoon. I clean in vinegar. hot rinse. on brew day I soak absolutely everything in bleach. I fill my kettle, and fermenter with ~1:50 solution, through everything too big to fit in the sink in them. Rinse brewpot, chiller, and spoon, brew, then while my wort is chilling I rinse my fermenter and lid extremely well. I also leave my kitchen sink full of the same solution and sanitize my kitchen with a sponge. After pouring I rinse my airlock really well. Load it with vodka and through the mess in the closet. Though only my 5th batch is in primary right now, I feel confident in my cleaning/sanitation regime.

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