[pure-silver] Re: Chemical substitution A CORRECTION!
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sat, 28 Apr 2007 19:15:47 -0700
----- Original Message -----
From: "BOB KISS" <bobkiss@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Saturday, April 28, 2007 6:44 PM
Subject: [pure-silver] Re: Chemical substitution A
CORRECTION!
DEAR RICHARD,
Just one favor...when you come out from under the bed,
PLEASE tell
me how much Sodium Citrate I should add per liter along
with the other
reagents to make stock solution of Hypo Clearing Agent. I
want to correct
my formula.
CHEERS!
BOB
I don't know. The only _authentic_ formula I have is
the one in the patent which does not include Sodium Citrate
only EDTA. The amount of citrate by weight listed in the
Kodak MSDS is the same as the EDTA but what is listed is a
5:1 _range_ not a specific amount. I suspect the exact
amount is not critical and I would try it at the same
strength as the EDTA namely 2.5 grams/liter for the
concentrate or 0.5 grams/liter if you mix working solution
directly.
I have since discovered a bunch of old correspondence
stored on a Zip disc including some from Doug Nishimura at
IPI on permanance. I am going through this stuff to see what
is relevant.
For instance, he contradicts a statement made somewhere in
the Kodak paper on wash aids, namely that the diffusion rate
of gelatin increases with swelling where the Kodak paper
speaks of minimising the swelling to make the diffusion path
as short as possible. This is simply beyond my chemical
knowledge. Doug Nishimura is a Phd chemist directly involved
with photographic chemistry so I give considerable weight to
anything he says.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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