[alt-photo] Re: Your Approach to Making Negs for Platinum Printing? Ideal Negative Contrast and Dmax?

[Don Bryant]

Have you printed a Stouffers step tablet yet with the palladium/platinum
mixture you plan to use on the paper you plan to use?  

Be prepared to exercise some elbow grease testing and then be prepared to
ask questions. 

Take one of your negatives used for silver printing and print that and see
how the palladium coating responds and see what that print will look like.
Print that with your standard palladium mixture at your standard printing
time and see how that works.

There are plenty of quotes about log density values needed for printing
palladium in the archives and around on the web. If you want numbers go look
at  Dick Arentz's webpage.

What you are asking isn't a trivial question and can't be summarized in a
paragraph or two.

If you want a SWAG, expose a piece of HP5+ normally and develop in pyro
developer @ 75F for about 10 minutes. You can pick any pyro developer you
like, BTW. In fact take a photo of scene that has a normal subject
brightness range of about 5 or 6 stops and the develop the negatives
starting with your normal development time for silver gelatin and then
increase the development of each negative by 20%. Then print the set with
your standard palladium mixture and process the paper. Compare the results.
You are on your way to determining what works without know the log density
of any of your negatives. 


Be sure your paper is properly humidified before printing each time.

These are just some of the preliminary steps.