[pure-silver] Re: fix good?
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 6 Feb 2008 16:49:55 -0800
----- Original Message -----
From: "Mark Blackwell" <mblackwell1958@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, February 06, 2008 3:48 PM
Subject: [pure-silver] fix good?
Well after a while I mixed a batch of fix only to forget
to turn down the water temp, and its now a very milky
white mixture in appearance. I have mixed fix with
water too hot before and it always seems to clear when it
cools off
Would it likely be ok to use this as is? Could it be
used, as a temp fix and then refix the negs later as
insurance?
This might also clear, but I tried to help on portion of
it along in the cooling process but it didn't seem to
help.
Any help would be appreciated.
I think its possible the heat may have caused the
thiosulfate to decompose. One of the steps in making
alum-hypo toner is to subject a mixture of hypo and alum to
high temperature water (above 160F) to get the hypo to
decompose. The sign of the decomposition is a milky
appearance.
Most old fixer formulas specify crystalline hypo which
is endothermic when it dissolves. That is, it cools the
water and is difficult to dissolve if the water does not
start out hot (Kodak specifies 125F). However, anhydrous
hypo has little heat of solution and should not be mixed
with water over about 90F. I am not sure if ammonium
thiosulfate is similar but its usually available as a liquid
concentrate because the powdered type does not have a long
shelf life. In any case, hypo is pretty cheap so IMO its not
worth taking a chance on it.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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