From: Nick Makris (nick@mcn.org)
Date: 04/13/00-01:44:25 PM Z
Hello again,
For those of you who followed my last two threads regarding PT/PD and ferric
oxalate degradation problems, the following is a synopsis of all the inputs,
my reaction/findings relative to those inputs (where appropriate) and my
current direction where it regards the preparation of ferric oxalate. As
you may know, Ferric Oxalate looses its effectiveness after 5-7 months and
the #2 solution goes bad even more quickly. As it turns out, my problem was
bad FO and upon investigating the best method of preparing the amounts that
I normally need during any give period (read that as 25ML), I found the best
way was to buy FO powder that readily dissolves in boiling distilled water.
First let me thank Carl W., Eric N., Sil H., Dick S. and Jeffrey M. (no
particular order) for their invaluable input to my questions and especially
for their ongoing comments which are much appreciated.
I was enlightened by one or more of the above about some very useful tidbits
which most of you may already know:
a.. Two different solutions of FO are not required if you normally have
a negative with good contrast. The addition of the #2 solution allows for
more contrast when your neg doesn't have enough.
b.. The #2 solutions contains Potassium Clorate in very minute
quantities which is very difficult to measure, without a very good scale,
when you are preparing quantities such as 25ML.
c.. Many of you only use the number one solution and add a contrast
agent such as H202 at the time you prepare the sensitizer and apply it to
the paper.
d.. It was suggested that I prepare my own FO by following the
procedures outlined by Eric Neilsen, Mike Ware, Jeffery Mathias or Dick
Sullivan. I can tell you that not being a chemist of any sort, I new I
would have to find some other alternative.
e.. B&S has powder kits for both the #1 & #2 solutions, but the #2
solution can't be readily mixed at less than the quantity of the kit which
does me no good.
f.. B&S has a powder similar (if not identical to) the #1 solution above
and can be mixed in quantities as little as 20ML or even less. The powder
keeps indefinitely and it meets my small quantity requirement. I have
purchase this package of FO powder.
g.. I have prepared my first 25ML batch (it was quite simple) and made
my first print with a very small drop of H202 as a contrast agent and I'm
happy to report that all the problems (poor contrast and no clearing) I
presumably had with bad FO have disappeared. In addition, I prepared the
first print from a known good print/neg combo and the two prints are
indistinguishable from one another.
Many thanks again,
Nick
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