Eric Neilsen (e.neilsen@worldnet.att.net)
Thu, 29 Jul 1999 17:11:45 -0500
Jeffrey, I failed to see how much time you allowed, if there was any,
between drying and exposure. I also have mentioned this before, but it does
take some time for paper to adjust to changes in RH. The wet paper would
have a hard time getting to an RH of 65%, with out first becoming drier
(less RH) than ambient conditions. That is why I dry my paper in a box @
100F for 10 to 12 minutes and then, add humidity back to the paper in my
humidity controlled box of 58% to 62% for at least 1/2 hour.
EJ Neilsen
"Jeffrey D. Mathias" wrote:
> 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/
-- Eric J. Neilsen 4101 Commerce Street, Suite #9 Dallas, TX 75226 214-827-8301 http://home.att.net/~e.neilsen
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