RE: Iron

For PT/PD I use a mild acid (citric or oxalic) first clearing bath. I
understand that this makes the iron salts more soluble. I then follow with
EDTA plus sodium sulfite clearing baths. Visually, at least, there is no
trace of coating solution.
Isn't Heico Permawash an ammonium + peroxide solution? Does it also work
for clearing iron salts?
                CHEERS!
                        BOB

 Please check my website: http://www.bobkiss.com/

-----Original Message-----
From: Kerik [mailto:kerik@kerik.com]
Sent: Monday, March 27, 2006 1:27 PM
To: alt-photo-process-L@usask.ca
Subject: Re: Iron

> I have a good sample of ten year old prints cleared in EDTA/sodium
> sulfite that look as good as the day they were made. I have not
> personally seen any EDTA cleared prints that have degraded, but by no
> means have I seen every
> print ever made and cleared with this method.

I think the issue may be that EDTA by itself doesn't work very well for
clearing pt/pd. I've had many comments from workshop students who had
previously tried EDTA alone and reported such problems, but adding sodium
sulfite to the mix did the trick. Approx one tablespoon each of EDTA and
sodium sulfite per liter works well on most papers, as does Kodak Hypo
Clearing Agent and Heico Permawash.

Kerik
Received on Mon Mar 27 11:47:24 2006