From: Jeffrey D. Mathias (jeffrey.d.mathias@att.net)
Date: 03/04/03-10:33:49 AM Z
"Christina Z. Anderson" wrote:
> 1. Why do most people use a bit more of the metal salts than the parts A/B
> combination? e.g.44/46 drops Part A+B/Part C instead of 44/44?
As Eric has mentioned the amounts of metal salt and sensitizer should be
balanced, typically resulting in an equal amount of drops. The likely
reason some have found better results by adding extra metal solution is
that their metal solutions are mixed too weak. My e-guide (from link
below) instructs how to balance the solutions. I feel it is more
important to know how to determine the strengths rather than what the
solution strengths are. This is important as too much metal will waste
expensive material and too little will result in weak prints. Many of
the published formulas do not provide enough metal in the mix. This not
only includes James and Crawford and Nadeau but Weese & Sullivan as
well. I have demonstrated by actual prints the balancing of various
metal salts and sensitizers. The results in actual prints confirmed
hypothesis of solution relationships. One should also take into account
the actual strength of a solution as this is also influenced by the
purity of the materials used.
> 2. Why does a line of demarcation occur with developing if you don't
> submerge the print in the developer evenly, if it is a develop- to-
> completion process?
I do not know the exact physics or chemistry, but this does happen and
is permanent in the situations when it has happen to me. I have caused
this from not pouring the solution continuously (stopping part way), air
bubbles under cloth, water splashed on predeveloped print, spit on
print, wet finger on print, and it is especially important to make sure
gloves are dry and to handle prints by edges. The laws of nature
dictate that the small drop of water will land in the middle of what
should be a uniform tone in the print.
> 3. I am getting so screwed up by the different proportions of chemicals in
> the developers and clears. Is it really that variably OK?
These proportions are not as critical for clearing, but additions to the
developer may wish to be controlled if one wishes consistent
repeatability. As Kerik states "Platinum printing is very easy". If
one wishes to have great control over consistency, they can achieve this
by carefully controlling parameters, including quality and amounts of
materials used, ambient conditions, skilled technique and such. Keep in
mind that steps like clearing may depend on the paper used (or other
materials.) One should routinely test the various aspects of the
process whenever new materials are introduced. What works for one may
not work as well for the other and versa visa.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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