[alt-photo] Re: humidity and contrast in the palladium/platinumprocesses

[EJ Photo]

Hi all, not to throw too much cold water on this experiment but there is
more to this than cool air, hot air, and guessing what RH is doing. Not to
mention that PT and PD have different reaction to each. There is also color
change with different levels of humidity. 

I have never found that blow drying a paper right after coating to be a good
thing. I don't blow dry with what some will call cool air. Different wattage
dryers put out different air flows, setting etc.  Different papers require,
by my observations, different times to let the coating soak into the paper. 

What do you have to measure the RH in your darkroom? just feeling it will
not cut it. Get your self a measuring device. about $35.00 should be plenty
to spend. Have your paper rest in that environment. 

Do you only use palladium? platinum? at what ratio? I dry my paper with a
low heat source for 10 minutes after a 2 to 3 minute soak in of the coating.
It then gets placed in a humidifying box for 1/2 hr.

Jeremy, I don't see much in Bob's suggestion to throw off the experiment. I
see little in either to determine an RH value so both methods lack
integrity. Seeing the suggesting might even lead me to say why teach some
one to make a bad coating? however the proof is in the pudding so if your
methods work, great, let's see what methods in more detail Francis already
employs. Does he have a Stouffer's or similar step wedge, if so what size?
more than 1?  densitometer or visual inspection. Regulation of electrical
source? Without accounting for variable to assume that francis will see the
effect of humidity only from print to print is not going to magically
happen. Does your suggest method produce enough variance to be seen?   

Francis,
in TNPP, (Weese and Sullivan) what pg are you referring to aging of FO? Not
all FO is the same and greater detailed explanation of your current
procedure might lead to a clue. 

Include your neg sandwich, holder, etc.      





Eric Neilsen
Eric Neilsen Photography
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