Re: Another Ziatype question

From: Martin Angerman <paleophoto@adelphia.net>
Subject: Re: Another Ziatype question
Date: Tue, 12 Oct 2004 18:43:56 -0700

> Actually, it does remove iron from the surface of stainless steel.

As I said before, EDTA + citric acid would remove iron but phosphoric
acid doesn't. It just converts iron to phosphate form, which has very
low solubility. People use this technique to increase corrosion
resistance of steel. Also, this is one classic technique to remove
phosphate from sewage water in tertiary treatment plants. (The problem
is that phosphates removed this way is hard to reuse. Phosphate supply
is rather limited.)

> For really tough stains, the company we contract with uses
> hydrofluoric acid (HF). That would clear a print so that even the
> paper is gone!!

HF is a favorite in semiconductor fabrication plants too... very
powerful cleaner.

--
Ryuji Suzuki
"You have to realize that junk is not the problem in and of itself.
Junk is the symptom, not the problem."
(Bob Dylan 1971; source: No Direction Home by Robert Shelton)