# Pt/Pd parameter questions on reading Arentz

Discussion in 'Alternative Processes' started by smieglitz, Sep 17, 2007.

1. ### smieglitzMember

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So I've decided Dick Arentz' book Platinum & Palladium Printing seems pretty thorough and is probably a good manual for learning about process calibration and other topics which may be transferable to other alternative processes. I am wondering if his definitions of certain parameters are taken as fairly universal, i.e., are most platinum printers speaking his language? I ask because of the wide variation in Density Ranges and Exposure Scales I see listed in other alternative process books for various processes.

So, I want to make sure I understand what he's saying and if it agrees with your practice.

First, he cites a DR of 1.4 as ideal for Pt and 1.65 for Pd and defines the DR of negatives as the density difference between zones VIII and III. His negative density values appear to be uncorrected for FBF where he refers to 0.30 as the "useful shadow density" (pg. 19) or ~ 0.20 above FBF, i.e., a net density of ~ 0.10. On the previous page, he states the "threshold for shadow density" is usually 0.15 to 0.25 as a result of base & fog & lens flare. So I'm thinking he is talking uncorrected gross density values (and his graphs seem to support that interpretation).

Second, he measures the exposure scale of the paper/emulsion combo based on a "90% black" value and a "discernible white" step value. It appears 90% black is two steps lighter than maximum or "Total Black" as he calls it. " Discernible White" appears to be the threshold light gray just slightly darker than paper or maximum white. Is that correct?

He also states that in order to find 90% black you need at least two shadow steps that have merged. But, once the ES is determined wouldn't you adjust the exposure so that max density was produced at step 1 in the minimum time?

And finally, the ES of the paper/emulsion will be the number of inclusive steps from 90% black to discernible white multiplied by 0.15. Is this how most Pt/Pd printers measure the ES?

Joe

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Joe,

Finally reading it, eh? I remember you saying that you had it, but hadn't gotten into it. I've always thought of it as a great book and as far as I know, his practice as described is pretty widely accepted. I may be wrong, but it has been a big help to me.

The sensitometry is where a lot get hung. Isn't there something about B+F and flare are not enough to factor into the print? Or is it just flare? Time to dig up the book again.
This is the way I have always understood it. -The white being the first step with some tonality.

I found that I can get too obsessed with the sensitometry aspect of it all. But then, I still have trouble creating a perfect palladium neg where I don't need a drop of Na2 to juice it a little. Not much, but I hope it helps some.

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3. ### Alan9940Member

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Hello Joe,

Dick's book on Pt/Pd printing is, I believe in most circles, considered the "bible" of this type of alternate process. Please keep in mind, though, that the information in this book is primarily directed to the production of in-camera negs for Pt/Pd printing and all the attendent information that goes along with this. Dick has been working quite closely with Mark Nelson producing digital negs for Pt/Pd printing. A couple of years ago I took a workshop with Mark and Dick and can assure you that some of the techniques Dick uses today are different than those presented in his classic book. Not sure how you're proceeding for Pt/Pd printing, but just something to keep in mind.

Hope this helps.

4. ### Don12x20Member

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Arentz Book Questions

"

>> Regards, Don Nelson

5. ### smieglitzMember

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Thanks for the replies. They have cleared up a lot for me.

I'm actually interested in his terminology and method for several processes including Pt/Pd, Salted Paper, Albumen, VDB, and Cyanotype. Though I may do a few inkjet negatives to show students the method, my personal primary interest is in-camera or duplicate negatives from interpositives.

Joe

6. ### smieglitzMember

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Another question popped into my head. If he defines the DR of negatives as the density difference between zones VIII and III, is he talking about a camera exposure Zone VIII, or is he calling his "discernible white" print value Zone VIII and looking at that density on the negative. Ditto on the other end. Is his Zone III also his "useful shadow density" of 0.30 above FBF?