RE: An exchange with Mike Ware (on Argyrotype)

I'm not a chemical genius at all but what I understood from Ryuji's
explanation belowis that even a trace amount is intolerable:
 
"...In short, oxygen in air can make very potent and active oxidizing
agents, such as peroxide and hydroxyl radical. These are collectively called
"active oxygen species" and are the same kind of things that they talk about
one possible mechanism of aging. The thing is that, the generation of
radicals is much much faster
when there is iron in the environment, because iron is a very active
catalyst for this type of reactions..."
 
The keyword that takes me to such a (maybe wrong) conclusion is: "catalyst".
Does it ring some bells?
 
See http://duke.usask.ca/~holtsg/photo/current/0303.htm for the whole
message.
 
Best regards,
Loris.

  _____

From: roger kockaerts [mailto:permadocument@yahoo.com]
Sent: 26 Mart 2006 Pazar 22:21
To: alt-photo-process-L@usask.ca
Subject: Re: An exchange with Mike Ware (on Argyrotype)

Dear list,
 
In silver printing we generally fight a war against trace thiosulfate and
have some efficient quantitative measuring techniques at our disposal.
Nothing of the sort exists (at my knowledge) to do the same with the iron
processes. It would be convenient if our chemical geniuses could come up
with a practical way to measure tolerable residual iron.
 
Warm greetings from Brussels,
Roger Kockaerts
Received on Sun Mar 26 13:47:09 2006