IMHO & IIRC, a lot of the oxygen that oxidizes the PMK (and all developers) is
dissolved in the water but filling and covering might help.
Alzo I think that one function of sodium sulfite in devs is as an antioxidant.
But using more has other effects on development such as being a complexing
agent causing dissolution of silver halide xtals. Too much may well throw PMK
off. I hope a photochemist might speak up here...
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Daneliuk
Sent: Friday, February 26, 2021 5:09 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: More (Semi) Standing Around
On 2/26/21 3:00 PM, `Richard Knoppow wrote:
I am not a chemist (which frustrates me no end) but my understanding is
that EDTA is a sequestering agent that attaches metals. For instance, EDTA is
used in hypo clearing agent to prevent a deposit of aluminum from the alum
hardener in the fixing bath (where it is used). It is also used to prevent
deposits of other metals such as magnesium salts that are in water.
I don't know what purpose it serves in the developer but think it does not
prevent oxidation.
The purpose of a developing agent is to absorb oxygen so I would think
anything that interferes with that too much would stop it from developing.
(It is a reducing agent). I think we have some actual chemists on the list
and I would love to hear from them.
