From: Christina Z. Anderson (tracez@mcn.net)
Date: 03/23/01-12:40:33 PM Z
This is called "bronzing", altho some call it solarizing. Previous notes
about this to the list have been inconclusive, and are as follows:
<snip>
"Bronzing: It would be nice if someone could quantify this bronzing
effect. It must depend on more than just over exposure. I have a
particular negative that requires almost a three hour exposure and the
uncovered edge coating does not display any signs of bronzing nor
solarization.. Typical exposures are 6.5 minutes with this light source> At
higher than 80F temperatures and higher than 70% RH, I have noticed some
random bronzing and solarization effects. However, I do not know of any
conditions that can consistently produce the bronzing effect."
<snip>
"My students consistently get the bronzing effect in the edge coating
and sometimes in the most open parts of the negative when they overexpose
palladium prints. Ernestine Ruben said that one or two drops of platinum
mixed with the palladium could prevent this from happening but we have not
tried that solution. I've seen the same kind of solarization - though I
hesitate to call it solarization because the areas where it happens go to
that bronze color rather than just losing density. And I can attest that a
little bit of platinum added to the palladium prevents it. Whether it
happens also seems to be related to the quantity of contrast agent. Sorry to
toss in yet another variable."
<snip>
John Barnier in his book says the cause can be not enough ferric
oxalate sensitizer used, so add more drops of it to the total sensitizer
solution. Or negative is too dense, necessitating an overly long exposure
time, so use a thinner negative requiring less exposure; or paper was not
dry before printing so dry over hot plate for a longer time.
Dick Arentz in his book says it occurs in areas of maximum exposure,
and you need to coat the palladium heavily, possibly with polyvinyl alcohol
in the sensitizer, or increase the proportion of metal to sensitizer (p.
90).
I, too, would love it if someone answered this question online
conclusively, because it has happened with me enough. And, with all the
books on the topic that I have, it is surprising it is not dealt with more
thoroughly, except that seems to me I never see it mentioned as being a
problem with platinum, just palladium, and so maybe the addition of a few
drops of platinum will do the trick, as per above.
Chris
> I have been printing Palladium for years. I use B&S kits, a velvet brush.
I
> have had no problems. This week I coated a new batch of paper, using a
> glass rod. I coated it at school, which means I did not have as clean a
> space as at home - but I was careful.
>
> When I developed the prints, the dark area glowed a sort of metallic
copper
> color. It did not go away with fixing. I have never seen this before. It
is
> sort of like Sabbatier. Only in the dark shadow areas are light and
> coppery. The rest of the image is fine. I printed another image at the
same
> time/same conditions which had no shadows. It didn't have any of this
effect.
>
> At first I suspected the glass rod (sorry B&S) but then I had a piece of
> paper from the same batch that was coated by velvet (I have been using the
> same velvet for years, so that is not it). It did the same thing with the
> shadow area of the print.
>
> Any insight? It was very cold (for Florida) - so perhaps my chemicals were
> cold when coating. Would that have done it? I know of no metal
> contamination - nothing I used was metal. Could there be a trace of other
> alt processes (cyanotype or Van Dyke or Sprint B&W chemicals) in the
> container I used. If so, it would have been minuscule - could that have
> done it?
>
> Thanks for any suggestions. I have coating another round and will print
> next week to see if it was a fluke.
>
> All the best,
>
> Ginger Sheridan
>
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