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

[Jeremy Moore]

Francis,

I will suggest a very easy test to see how relative humidity affects YOUR
printing.

Variable: Humidity

Experimental Model:
1. Coat a piece of paper and immediately blow dry it (preferably with cool
air so as not to introduce another variable, but you do want forced air)
then expose it.
2. Process as normal.
3. Coat a 2nd sheet of paper and immediately blow dry it (dry it in the same
manner as you dried the first one). Re-humidify this paper by holding it
over steamy water from a tap or heated water on a stove or a humidifier if
you have one. Humidify the paper until it is as damp as you think you can
make it without ruining your digital negative then expose it.
4. Process as normal.
5. Let both prints fully dry then compare and report back to us!

Notes: Keep everything as constant as possible--even to the point of paper
from the same batch or coating 2 halves of the same sheet. Print an image
with long, smooth tonal scale. Include a step wedge in the prints--both a
Stouffer if you have one and a test wedge created in Photoshop that is part
of your digital negative.

On Fri, May 21, 2010 at 9:49 AM, francis schanberger <frangst at gmail.com>wrote:

> Dear AltList,
>
> What is the working relationship of relative humidity to the final contrast
> in either a palladium developing out print or a printing out print?
>
> I've been struggling with contrast and have always been rather
> laissez-faire
> in monitoring and adjusting humidity due to the dungeon like qualities of
> my
> dim room.
>
> In regards to developers, does ammonium citrate ever get too old? Could a
> trend of producing low contrast images independent of drop mixtures
> indicate
> exhausted developer? I was reading in the Weese / Sullivan "New Platinum
> Print" book that older ferric oxalate tends to have higher not lower
> contrast.
>
> -francis
>
>
>
>
> --
> francis schanberger
>
> www.frangst.com
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