From: Jeffrey D. Mathias (jeffrey.d.mathias@att.net)
Date: 11/13/02-01:06:50 PM Z
Jeff Buck wrote:
> ... after doing platinum/palladium for about fifteen months
> now, I find if very difficult to achieve. ...
> the humidity is in the range of 60% to 70%.
> In each instance, the paper has been laying out in the area of that
> temp and humidity for a few hours; ...
> There were notable differences in the overall darkness of the
> prints and in degree of contrast.
> Would you expect discernible differences working within these
> variations in temp and humidity?
> How do you measure the temperature of the FO and platinum or palladium?
Pt/Pd printing results can be very consistent if one is careful and
consistent in their utilization of proper technique and procedures. You
should certainly evaluate your technique and procedures even if some of
this may be from your equipment (lamps or such).
>From your message there are two concerns that may affect consistency.
For POP a humidity of 60% or more can cause problems and do so
inconsistently. Keeping the coated paper at high humidity or
temperature for several hours can also cause problems. Even 4 hours
with the coating dry and cool can incur noticeable degradation.
Depending on other factors, temperatures over 70F might cause
inconsistencies (I try to keep my coating and exposure at 60F ambient,
but the solutions may be warmed as required.)
Liam is correct in mentioning coating consistency. This can range from
coating efficiency (material wasted in brush, etc.), to coating
application (how much per area), to solution strengths. Even if your
solutions are mixed to the correct solution strengths, they may not be
so at the temperature used and may require warming as indicated by Eric.
My e-guide from the link below can provide much information on producing
consistent Pt/Pd prints.
To answer your second question (as the first is answered above): there
should be no problem with using a glass or plastic thermometer. Just
keep it clean; rinse and wipe dry with a clean paper towel after
removing from each solution. If no contact with the solution is
desired, place the bottles of solutions and thermometer into a water
bath which can be temperature controlled and wait for thermal
equilibrium. Of course, when stored the solutions will be the
temperature of the ambient.
Additionally, I have sometimes found differences in the print when the
order of adding the ingredients to the coating mixture is changed,
especially with contrast agents. Also contrast agents should be added
only when mixing the coating solution for use and not added to the
stored stock solutions.
Remember also that many of the things you establish in your technique
and procedures may need to be altered when something changes, like the
paper used.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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