Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Thu, 29 Jul 1999 16:53:23 -0400
Carl et all,
Had some time during printing today. I have results from a preliminary
comparison of what will be called "wet" and "dry" exposure.
"Wet" exposure means that the relative humidity of the coating was at
ambient and rather high when exposed. Drying was accomplished by
blowing ambient air over coating until just dry. This coating was
prepared and dried at an ambient RH of 65% (temp 82F).
"Dry" exposure means that the ambient RH was lowered and the print dried
by blowing air with medium heat over the coating to dry as much as
practicable. This coating was prepared and heat dried at an ambient RH
of 51% (temp 82F).
Two prints were made and compared.
Paper was Crane's lot # 5302 (the one in question)(AKA parchment
Business card stock; AKA Cover 90; AKA pltinotype)
Coating was 9 drops FO (27%), 6 drops K2PdCl4 solution (19%), 3 drops
K2PtCl4 solution (24%), 1 drop Ammonium Dichromate solution (0.25%)
Paper was humidified
Coatings were applied by brush and covered enough area for a 4x5, a
21-step, and boarders.
Coatings were dried as above
Exposed for 6 minutes with BL type lamps.
Developed in Potassium Oxalate
Rinse/Pre-clear in water bath
Cleared with phosphoric acid baths for total of 30 minutes
rinsed in buffered water, washed, dried
OBSERVATIONS:
PRINTOUT
+ The "wet" print had much more print out. The printout was very dark
for the blacks and very high contrast. I suspect that this is a
determining factor in the separation of shadow values. (See findings
below)
DARK AREAS
"dry" print ==
+ Has a darker boarder, which is also warmer and has more apparent
depth and substance.
+ Does not show any solarization effect.
+ Speed point - difference from step 2 to 3.
"wet" print ==
+ The dark area (boarder) is a more neutral black and appears flatter.
+ Shows some solarization effect of boarder and steps 0, 1, 2, and
possibly 3 with reflected light only. Transmitted light does not show a
solarization effect. Whether this is really solarization is not known.
+ Speed point - could be from step 3 to 4 since step 3 may be off and
definite difference from step 4 to 5. (Steps are about ½ stop.)
CONTRAST
+ The "dry" print seemed to reach a zone VIII between steps 15 and 16
with clear discrimination of 17 and 18.
+ The "wet" print seemed to reach a zone VIII around step 17 with clear
discrimination of 18, 19, and some discrimination of 20.
VALUES AND TONALITY
+ The "wet" print mid and upper values have a warmer color while the
lower values are more neutral.
+ The tones look smother in the "dry" print.
+ While both prints have good shadow detail, the "wet" print seems to
have better discrimination in the shadows (especially in bushes and tree
trunks).
+ Even though over all contrast is about the same and the "dry" print
has better blacks, the "wet" print shows more contrast (or
discrimination) in the dark areas of the image (not in the 21-step).
FINDINGS:
The "wet" print is about 3/4 stop faster.
The "wet" and "dry" prints have about the same contrast.
The "dry" print has more depth and substance while the "wet" print may
be solarizing.
The "dry" print has warmer dark values; the "wet" print has warmer mid
and high values.
The "wet" print has better shadow separation.
COMMENTS:
If what appears to be solarization could be stopped, the "wet" print
could be superior. If a better printout could be obtained with the
"dry" print, then it could be superior. As they are now either method
can produce a great print. It becomes a mater of trading nuances (some
of them not so tiny.)
DISCLAIMER:
Keep in mind that other papers or chemistry may behave differently.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:40:38