Yes, in acid some elemental selenium can be evolved from the
toner which causes a "peach" colored stain which can not be
remove. The whole idea of diluting KRST in HCA was to avoid this.
Washing before toning also avoids it.
Note, the acid in fixing baths is for the hardener or to stop
development, thiosulfate is not dependent on pH, it will fix in
an alkaline or neutral bath just fine. A "plain" fixing bath
should have some sulfite in it to prevent decomposition of the
thiosulfate and to prevent staining from carried over developer.
In the distant past the performance of the hardener was very
important because emulsions were not hardened nearly as much in
manufacture as they are now. The recommendations for very long
fixing times were to give the hardener time to work. The lifetime
of fixing baths was often judged by the performance of the
hardener rather than the fixer.
On 2/16/2021 7:53 AM, BOB KISS wrote:
Zack's post reminded me of some research I read a while back...that it was the acidity from the hardener as well as residual fixer that interacted with the emulsion and KRST to produce the stains. That is why, as Robert said, rinse, hypoclear, wash, THEN KRST, then wash again, works best to prevent stains.
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Daneliuk
Sent: Tuesday, February 16, 2021 10:32 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: What Is Your Fix/Clear/Toning Doctrine
On 2/16/21 6:51 AM, BOB KISS wrote:
> DEAR ROBERT,
>
> I got staining in the whites of my fiber based prints often when I combined the Rapid Selenium Toner with the HCA. Never got it following your sequence below.
>
> CHEERS!
>
> BOB
>
Bob -
This was also my experience. I have read that KRST will stain if a
print is underfixed.
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your account (the same e-mail address and password you set-up when you subscribed,) and unsubscribe from there.
