jeffbuck@swcp.com
Date: 11/13/02-01:21:18 PM Z
Jeffrey: Thanks for the information and the link. -jb
"Jeffrey D. Mathias" <jeffrey.d.mathias@att.net> said:
> 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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