Re: Another Ziatype question

Has anyone tried combining clearing chemicals?

We have a lot of stainless steel piping at work. Part of the major
maintenance is called "passivation." Essentially it removes any surface
iron oxide, giving a chrome and nickel rich surface. The preferred
chemicals are citric acid with EDTA, followed by citric acid alone, then
phosphoric. They are used in MUCH stronger concentrations than what you
need to clear a Ziatype or Pt/Pd. We get citric acid in 50% w/v solutions.
The final concentration is usually in excess of 15%, and used hot.

As far as to which type of EDTA to use, as a general chemistry reagent, the
main difference is in the solubility. Once again, usually in much greater
concentrations than for printing.

Martin Angerman

----- Original Message -----
From: "Jeffrey D. Mathias" <jeffrey.d.mathias@att.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Monday, October 11, 2004 7:33 PM
Subject: Re: Another Ziatype question

> Sandy King wrote:
> > ...
> > As for the oxalic acid soak, .... The soak appears to break down and
> > remove the surface sizing, the result being a more granular or textured
> > look. ...
>
> I have also experienced this and suggest it is easier to find a paper or
> fabric that works rather than trying to fix one that doesn't. But I can
> understand if that one paper has just the look wanted.
>
> --
> Jeffrey D. Mathias
> http://home.att.net/~jeffrey.d.mathias/
>
>
Received on Mon Oct 11 21:42:24 2004