Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Thu, 01 Jul 1999 13:44:25 -0400
The following concerns producing Zia type Pt/Pd prints.
Producing a couple hundred business cards does provide an opportunity to
verify previous results and to experiment. Producing cards is a
generally "quick & dirty" operation, although work is always preformed
careful enough to be consistent. An observation of interest did come
about.
Previously, there had been some difficulties get weak prints at 88F and
65%RH. (If you recall good prints were then obtained with sunlight.)
The first set of cards were made at 77F and 67%RH and resulted in weak
prints (including the brush marks). For the next set, some heat was
added during drying the coating (just to do it, knowing it would reduce
the humidity in the paper). This resulted in much stronger prints. So
next the RH was lowered to 60% and another set coated. The result was
good prints. Several others were made at 80F and 60%RH (warmer because
of the dehumidifier running) all resulting in good prints.
Now not all prints made at 65%RH and over are weak. I got some very
good strong prints under these conditions, but not without unsuspected
rejects. Definitely there is an inconsistent ability to produce prints
that are not weak. To me this means that the higher relative humidity
is going to inconsistently produce weak prints. Most likely something
in addition to the RH is at play. I will most likely not research this
further, but there is a strong recommendation the high relative humidity
should be avoided. Just how high may depend on many things including
paper, chemistry, temperature, light source, and whatever.
I have also noticed a post concerning the white specks mentioned some
sticking of the coating to the negative during printing. It is strongly
cautioned that the level of relative humidity in the coating for these
cases is way beyond that amount which may inconsistently produce weak
prints.
It would be suggested that coating be made no higher than about 60%RH to
consistently get good strong prints. Has anyone else noticed this?
Nze, have you noticed anything like this? (Previous posts indicate that
Nze has made many Zia prints at various humidity.)
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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