RE: palladium drydown and developer

Hi all,
        It seems that there are some techniques for minimizing dry down and the
discussion of the causes is very interesting but I feel, if you've got it,
how do you live with it? Though I appreciate the commercial lab's
techniques, I use a microwave oven (which I learned reading Ansel in the
80s). Used, they are pretty cheap and work very well for drying test
strips. I lay the strip across the print in such a way to include the
important highlight, midtone and shadow, when possible. I carry it through
the process to about half way through the clearing, give it a 5 minute wash
and then microwave it for two or three minutes in one minute steps,
depending on the size of the strip. Voila! A dried down print. I judge my
densities and choose my exposure accordingly. This has proved to be VERY
reliable and I hardly ever have a print that isn't the density I have
chosen. Whether I have chosen well is another question ;-)) but I get what
I asked for!
        I mentioned in a post about 1 1/2 to two years ago that I found that prints
from digital negatives had a curious drying phenomenon that prints from
camera original negs did not. In prints from digital negs, the shadows lost
density but so did the highlights...they both got lighter!!! In prints from
camera original negs the dry down was more standard, i.e. the highlights got
darker and the shadows lighter.
                        CHEERS!
                                BOB

 Please check my website: http://www.bobkiss.com/

"Live as if you are going to die tomorrow. Learn as if you are going to
live forever". Mahatma Gandhi

-----Original Message-----
From: Loris Medici [mailto:mail@loris.medici.name]
Sent: Friday, July 21, 2006 7:48 AM
To: alt-photo-process-l@usask.ca
Subject: RE: palladium drydown and developer

Hi Clay,

My take / understanding is: when you coat the paper with some kind of
reflective medium (gelatine, gum, wax and polyurethane wood finish as I do),
the reason of the darkening and contrast increse in the shadows is caused by
the fact that the higher refractive index of the coat causes some of the
refracting light stay in the layer... Think of the mirror effect water
causes when the light hits it surface from beneath with angles lower than xx
(was it 38? - don't remember exactly - whatever you understand what I mean).
Since less light is reflected back (and kept in the coating), density
increases.

Maybe your theory with fibers is also effective in this phenomenon but I
think the actual/main reason/cause of the dmax increase is what I describe
above.

Regards,
Loris.

-----Original Message-----
From: Clay [mailto:wcharmon@wt.net]
Sent: 21 Temmuz 2006 Cuma 13:51
To: alt-photo-process-l@usask.ca
Subject: Re: palladium drydown and developer

...

The other phenomenon that has not been mentioned is the microscopic
'fuzzing' of the paper surface that occurs as paper dries. This seems to
affect the dark shadow areas much more. It is really more accurately called
'dry-up'. If you slap a wet pt/pd print on a reflection densitometer, you
will get a much higher reading (in the
1.8 range) than you will a few hours later after it has dried. The tiny
fibers of the paper then stand proud and cause a loss of reflection density
that in the best of cases will give you reflection densities in the
neighborhood of 1.4-1.5. This is almost a full stop of reflection density
loss.

As to what can be done to mitigate this effect, I have found that very light
gelatin sizing (in the 1% range) can help to a degree.
Another approach is to deal with this after the print is dry and apply
either wax or subsequent gum coats. I have a waxed vellum print that has
measured Dmax of 1.9 using several layers of Gamblin cold wax medium.

My personal preference is for additional layers of expose gum, since it
offers so many options for color manipulation of the image.
Finally, a coat of Liquitex Gloss medium diluted 1:8 will also have the
effect of causing a measurable (though relatively minor half
stop) increase in Dmax. Again, I think this is because it causes the
microscopic fibers to lay down and behave.

...
Received on 07/21/06-06:10:17 AM Z