Post Number: 1829
Posted From: 18.104.22.168
|Posted on Wednesday, October 21, 2009 - 05:44 pm: ||
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.
Post Number: 7287
Posted From: 22.214.171.124
|Posted on Wednesday, October 21, 2009 - 07:52 pm: ||
I'd need to hear the chemistry behind that claim before I could accept it as true.
Post Number: 10833
Posted From: 126.96.36.199
|Posted on Wednesday, October 21, 2009 - 09:50 pm: ||
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.
Post Number: 2269
Posted From: 188.8.131.52
|Posted on Thursday, October 22, 2009 - 12:02 am: ||
* 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.
Post Number: 1798
Posted From: 184.108.40.206
|Posted on Thursday, October 22, 2009 - 05:56 pm: ||
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
Post Number: 2853
Posted From: 220.127.116.11
|Posted on Thursday, October 22, 2009 - 06:02 pm: ||
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.
Post Number: 1800
Posted From: 18.104.22.168
|Posted on Thursday, October 22, 2009 - 08:23 pm: ||
I googled "Iodine Stainless Steel" (w/o quotes) and found this:
"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:
* astatine (very unstable.)"
"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.
Post Number: 1833
Posted From: 22.214.171.124
|Posted on Friday, October 23, 2009 - 12:09 am: ||
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?!?
Post Number: 132
Posted From: 126.96.36.199
|Posted on Friday, October 23, 2009 - 02:36 pm: ||
"halogen salts, especially chlorides easily penetrate this passive film and will allow corrosive attack to occur."
Does that mean we shouldn't keg Gose?
Post Number: 929
Posted From: 188.8.131.52
|Posted on Friday, October 23, 2009 - 03:03 pm: ||
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.