| Author |
Message |
    
dhacker
Senior Member
Username: Dhacker
Post Number: 1829
Registered: 11-2002
Posted From: 72.4.22.214
| | Posted on Wednesday, October 21, 2009 - 05:44 pm: | 
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In the latest issue of BYO John Blichmann cautions against leaving Iodophor solution in a stainless vessel for too long. Is there some issue? Bleach, yes, but Iodophor??
I usually start heating my strike water and immediately prepare my 1/2 bbl fermentor with a full capacity dilution of Iodophor solution and it stays in there until I start chilling the wort, so it could be in the keg several hours before I drain it . . more a matter of timeline convenience than necessity if there is indeed a problem with prolonged contact. |
Denny Conn
Senior Member
Username: Denny
Post Number: 7287
Registered: 01-2001
Posted From: 75.145.77.185
| | Posted on Wednesday, October 21, 2009 - 07:52 pm: |
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I'd need to hear the chemistry behind that claim before I could accept it as true. |
Bill Pierce
Moderator
Username: Billpierce
Post Number: 10833
Registered: 01-2002
Posted From: 24.141.103.148
| | Posted on Wednesday, October 21, 2009 - 09:50 pm: |
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John Blichmann is an engineer, and seemingly a good one, but he is not a metallurgist. I generally defer to John Palmer on these issues, and he doesn't seem to find any problem with exposing stainless to properly diluted concentrations of iodophor. |
Graham Cox
Senior Member
Username: T2driver
Post Number: 2269
Registered: 11-2004
Posted From: 72.15.96.251
| | Posted on Thursday, October 22, 2009 - 12:02 am: |
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* WARNING * name-dropping to follow * WARNING *
Know them both. I'd like to see them in a cage match. Blichmann's pretty wiry, but Palmer looks like he could take some punishment and still keep going. Palmer often wears glasses, so maybe Blichmann could blind him right off. It would be an interesting fight.  |
Paul Edwards
Senior Member
Username: Pedwards
Post Number: 1798
Registered: 03-2003
Posted From: 76.252.4.196
| | Posted on Thursday, October 22, 2009 - 05:56 pm: |
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Hmmmm,
The only thing I can think of (and I'm neither a chemist nor a metallurgist) is that chlorine and iodine are both halogens, and as such, share some similar properties.
Oh, Graham, John Blichmann wears glasses, too.
I'd call the cage match a draw |
Bob Wall
Senior Member
Username: Brewdudebob
Post Number: 2853
Registered: 11-2004
Posted From: 98.192.7.62
| | Posted on Thursday, October 22, 2009 - 06:02 pm: |
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I tried doing a Goggle search using "iodine" "Stainless Steel" "corrosion" and a few other keywords. The only results I got were a bunch of techno-babble gobblety-gook research results written in Urdu, translated into Aramaic, then into Morse Code. In other words, not much is written coherently on the reaction of iodine on stainless steel. |
Paul Edwards
Senior Member
Username: Pedwards
Post Number: 1800
Registered: 03-2003
Posted From: 76.252.4.196
| | Posted on Thursday, October 22, 2009 - 08:23 pm: |
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I googled "Iodine Stainless Steel" (w/o quotes) and found this:
http://www.mcnallyinstitute.com/04-html/4-1.html
"Unlike aluminum or silver this passive film is invisible in stainless steel. It's created when oxygen combines with the chrome in the stainless to form chrome oxide which is more commonly called "ceramic". This protective oxide or ceramic coating is common to most corrosion resistant materials.
Halogen salts, especially chlorides easily penetrate this passive film and will allow corrosive attack to occur. The halogens are easy to recognize because they end in the letters "ine". Listed in order of their activity they are:
* fluorine
* chlorine
* bromine
* iodine
* astatine (very unstable.)"
Also this:
http://www.estainlesssteel.com/corrosion.shtml
"1. Uniform Attack - also known as general corrosion, this type of corrosion occurs when there is an overall breakdown of the passive film. The entire surface of the metal will show a uniform sponge like appearance. Halogens penetrate the passive film of stainless and allow corrosion to occur. These halogens are easily recognizable, because they end with "-ine". Fluorine, chlorine, bromine, iodine and astatine are some of the most active."
So that would say that Iodine contact might indeed be a problem, but not nearly as big a problem as chlorine. |
dhacker
Senior Member
Username: Dhacker
Post Number: 1833
Registered: 11-2002
Posted From: 98.66.33.82
| | Posted on Friday, October 23, 2009 - 12:09 am: |
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It never ends, does it?
Just when you think you've got a handle on it and good procedure, some other morsel surfaces to derail you . . whether real or imagined.
Now every time I sanitize my stainless fermentor, I'll wonder . . what's going on at the molecular level?!?
 |
Marc Rehfuss
Member
Username: Marc_rehfuss
Post Number: 132
Registered: 03-2003
Posted From: 199.133.212.53
| | Posted on Friday, October 23, 2009 - 02:36 pm: |
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"halogen salts, especially chlorides easily penetrate this passive film and will allow corrosive attack to occur."
Does that mean we shouldn't keg Gose?  |
Patrick C.
Advanced Member
Username: Patrickc
Post Number: 929
Registered: 01-2001
Posted From: 99.170.160.145
| | Posted on Friday, October 23, 2009 - 03:03 pm: |
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All kinds of •••• is going on at the molecular level, but it may not have any effect as far we are concerned- i.e. no pitting, pinholes or other macro-level damage. I wouldn't be concerned with exposure of a few hours, or even a few weeks. After longer exposures you might see some damage under the microscope, but for homebrewing I don't think you'll have to worry about it. |
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