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Re: platinum/palladium coating - exposing POP
Istvan Bibo wrote:
> ...I have no consistent procedure
> yet (still experimenting), but I try to keep conditions the same in one
> printing session. In one session I dried the prints at the Rh of about 60%
> the next time I dried it with a hair drier and then exposed it.
> Overheating, for some reason, is not a problem for me. I use 4 black light
> tubes and they appearantly do not heat the printing frame significantly....
Drying the coating and paper to the proper RH (Relative Humidity) can be
tricky. I have found the most consistent way is to fix the RH in the
room (sonic misters and/or dehumidifiers) then use a hair drier with NO
heat and low blow. (For low RH conditions and to get "bone dry", I use
medium heat and medium blow.) I does take some time to dry the coating,
but this provides accurate consistent results. If the ambient RH is
different than that desired for the coating, this can be a problem as
the paper can change or exchange moisture rather quickly. This can be
observed by placing the paper on a scale and watching it gain or loose
weight. Without a consistent procedure it is questionable if conditions
are kept the same, even in one printing session.
The black light (BL) tubes can cause a heating problem (these are the
type of lights I use). Consider that less than what you consider to be
"significant" heating might still cause the problem. And remember the
heating is cumulative. Until I had noticed that only the first prints
were consistently as expected, I did not expect that the fluorescent UV
lamps would cause enough heating. Also a vinyl sheet placed behind the
paper in the printing frame will help.
A footnote:
Contrary to what some may wish others to think, I do make good Pt/Pd
prints and share that knowledge freely. I also do it on-list so others
can learn or contribute and can agree or disagree so as to further
promote the understanding of the Pt/Pd process. My guide is on-line and
contains information which is proven to work consistently well. The
information is updated and modified as desired or needed and includes
more than fifteen years of experience with the Pt/Pd process. My way is
likely not the only way, but it is a way that works. In the guide, it
is preferred to disclose universal ways of discovering and learning the
information and skills necessary.
--
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/