[pure-silver] Re: sodium sulfite and air

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <pure-silver@xxxxxxxxxxxxx>
  • Date: Thu, 18 Feb 2010 09:05:30 -0800


----- Original Message ----- From: "Dennis Purdy" <dlp4777@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, February 17, 2010 10:07 AM
Subject: [pure-silver] sodium sulfite and air


I know that Kodak Hypo clear doesn't last all that long in a tray, like 24 hours or so. I think I read that it is due to changing PH. So my question is, if I mix up a quantity of Beutlers developer part A, with the components of Metol and Sodium Sulfite, and I let it sit out overnight in a open topped gallon graduate, will it go off?
Thanks to anyone who knows the answer.
Dennis Purdy

Wash aid is mostly sodium sulfite. Sulfite absorbs oxygen from the air and becomes sulfate. While sulfate does no harm it is not anywhere near as effective as a wash aid as is sulfite. The change in KHCA or other sulfite wash aids is due to oxygen absorption. There may be a change in pH as well but this is not the reason for the loss of effectiveness. Working solution KHCA should be viewed as an expendible. I have not looked at its tray life but I would guess it at more like 8 hours than 24.

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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