[pure-silver] Re: Tetenal Wash aid
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sat, 17 Sep 2005 05:23:38 -0700
----- Original Message -----
From: "Stefan Kahlert" <s.kahlert@xxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Saturday, September 17, 2005 3:47 AM
Subject: [pure-silver] Re: Tetenal Wash aid
Hi Daniel,
Tetenal's washaid comprises soda and water.
best
Stefan
Am 17 Sep 2005 um 10:20, schrieb Daniel Bouzard :
Hello every body
Does some one know what is the formula of the wash
aid sold by
Tetenal.
The pH of the working solution is around 10 and it should
be different
from the Ilford'formulation. It is used after 1+19
dilution and for
2mn.
Daniel
If the above is correct it is a standard, old fashioned,
alkaline bath. You can use 2% sodium carbonate or 2% sodium
metaborate, or 2% Ammonium carbonate (old Kodak
recommendation).
Kodak Hypo Clearing Agent is 2% Sodium Sulfite buffered to
pH 7 with the addition of small amounts of EDTA tetra sodium
salt and Sodium citrate. The latter two are sequestering
agents to prevent scumming from minerals in the water
although Sodium citrate is itself a wash aid. Sodium sulfite
is more effective than the other salts because it has a
specific ion exchange effect on thiosulfate and silver
complexes which carbonates do not have. The buffering
prevents excessive emulsion swelling and preserves the
hardening action of alum hardener while eliminating its
mordanting effect on hypo and silver complexes. Ilford wash
aid appears to be sodium sulfite without the buffering or
sequestering agents.
The 2% concentration is for working solutions.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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