From: Eric Neilsen (e.neilsen@worldnet.att.net)
Date: 03/01/01-12:22:06 AM Z
Jeffrey D. Mathias wrote:
> "Christina Z. Anderson" wrote:
>
>> If you have a stoppered bottle of palladium that is 3/4 full, will it still
>> be good after one year?
>
>
> Yes. (I am assuming you mean a double salt of Pd in solution, nothing
> else added.) The only change would be if water evaporates effectively
> increasing the strength of the solution. Note that some strengths of
> solution will not stay completely dissolved at ambient temperatures and
> may need warming in a water bath.
>
>
>> What might be the cause of two round, about the size of jelly bellies,
>> circles of lighter, lesser exposed palladium? ...
>> did you guys ever figure out what the actual cause of bronzing ... and is it
>> true that the addition of a bit (how much of a bit) of platinum to the
>> palladium brew will stop this from happening?
>
>
> The lighter spots or splotches and the "bronzing" can be attributed to
> improper coating. When too much of the coating mixture puddles or dries
> too quickly leaving a thick layer on the surface rather than in the
> upper surface of the paper, both these effects can occur (individually
> or together). The "bronzing" may also occur more easily when certain
> materials are used. I have made many Pd prints without Pt without any
> problems, and have noted "bronzing" when Pt was also present.
>
> Other causes of light blotches could be foreign material (such as finger
> oil, hand lotion, misc. chemicals) on the paper. Some papers coat
> blotchy all over.
>
> In some instances "bronzing" may be thought to be solarization, but is
> likely caused with high humidity, high temperature exposures. This type
> of "bronzing" can occur no mater how good the coating is.
Chris, All of Jeffrey's observations are right on.
I would add that the blotches may be caused by oil getting
on to either the paper or coating rod. They can also occur
when a bad or inconsistent sizing is applied. I have not
however seen that with Cranes.
The palladium double salts of ammonium and sodium (60%) have
very high solubility and if kept in a tightly seal jar
should be fine. If you are using a bottle that has some
solids around the top, use a dampened paper towel to clean
and remove them. While they will more than likely return to
solution if placed in the bottle, they may introduce a
contaminate and should be removed and discarded.
The tendency to bronze can be from a thin coating, which is
faster than thicker coatings, and therefore will be reacted
on more quickly. It will not be able to give a good black.
A thin coat of sensitizer with or without pt will look weak,
and may be called "bronzing". With the price of palladium
these days, I would certainly think that a pinch of pt may
help. I rarely use less than 25% pt. The high temperature/
high humidity are both friends to palladiums speed.
Hope that helps
EJ Neilsen
-- Eric J. Neilsen 4101 Commerce Street, Suite #9 Dallas, TX 75226 214-827-8301 http://e.neilsen.home.att.net http://www.ericneilsenphotography.com
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