A question for our resident sensitometry experts

[robshepherd]

In Dick Arentz's book "Platinum and Palladium Printing" he published data for use with FP4 and D-76 to yield a negative with a density range of 1.4. I tried to use these numbers, but they were way off for me, and I'm curious as to why.
He uses subject brightness range, and if I understand, that is BTZS nomenclature, which I'm barely familiar with. I use 5 stops as a normal range, whereas he considers SBR 7 a normal negative. I meter the deepest shadow and call it zone III, then place highlights on zone VIII for a N negative.

How far off are the numbers for me? Well, I tried developing a N negative for the recommended 12 minutes at 1:1. On the densitometer I could only get a highlight of about 1.5. Not even close. After a number of trials, I found that if I use D-76 straight, I need to develop for 16 minutes to get a dense enough highlight for the pt/pd process, and a 1.3 or 1.4 range. On Dick's chart (attached) that development represents more than a plus-one.

All of this is OK with me, because it's the result I'm after, and if it takes 16 minutes, I'm fine with that.

My question is simply how does one explain such a dramatic difference between my numbers and his? What would I need to do to make his numbers work for me? Doesn't 12 minutes at 1:1 seem short and weak for the densities we're looking for?

It's an excellent book, by the way! Thank you for considering my questions.

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[Doug Herta]

Hey Rob,

I follow Dick Arentz's book and technique for my own work and agree it is an excellent resource. My experience is similar - to get the higher density and density range for pt/pd I am way past the recommended times that I see published in Arentz's book as well as the recommendations in Unblinkingeye.com and other resources. I use Sandy King's pyrocat recipe and FP4.

That said, since I am getting good separation in my negatives I have learned to stop worrying and let the results speak for themselves. The densitometer indicates the film is producing the proper density increases for subsequently longer development times. I closed in on the right ranges for silver and for pd/pt. This is why there are so many warnings to do your own testing and only use published times as a starting point. I am working in a (cool) Seattle basement using Seattle tap water on the lowest speed setting of a Jobo CPP.

[robshepherd]

Doug, glad to hear you had similar results! And I agree, at the end of the day you need to develop for as long as it takes to get the result. I have been doing some kallitypes here lately, and everything I learned about printing pt/pd applies. I feel like I'm getting priced out of the palladium market, hence exploring another process. I'm just up the road from you in Bellingham! Thanks, Rob

[Drew Wiley]

I'm not qualified to talk about pt/pd per se, but 12 min sounds more like what would deliver just a bit above typical N results for silver printing with FP4, and you no doubt want more density than that.

[robshepherd]

You're right about that Drew. There must be something I'm misunderstanding about the numbers on the chart. I say this because Dick is clearly an accomplished printer with this process!

[Doug Herta]

Doug, glad to hear you had similar results! And I agree, at the end of the day you need to develop for as long as it takes to get the result. I have been doing some kallitypes here lately, and everything I learned about printing pt/pd applies. I feel like I'm getting priced out of the palladium market, hence exploring another process. I'm just up the road from you in Bellingham! Thanks, Rob

Hey Rob,

I got priced out of platinum and have a large stash of palladium to keep me going for awhile. I started with kallitypes about 15 years ago and may move back - I think it is an excellent process. There are probably a lot of pt/pd prints out there that started as kallitypes and were toned pt/pd. That is one cost-saving strategy - make kallitypes and the ones that turn out well get toned. The Dick Stevens' kallitype book "Making Kallitypes: a Definitive Guide" is great but it is outlandishly expensive now (out of print). I kept borrowing the copy at the library until one came on the market cheap and I snapped it up. Take Care! Doug

[robshepherd]

Thanks for the info Doug. I've been thinking about Stevens' book. May try to look at one through inter-library loan, when that's available again. I have a small stash of palladium here too, not a lot, but enough to make toners for a long time! I have gold-toned a few now and I like that look as well. Regards, Rob

[Pere Casals]

with FP4 and D-76 to yield a negative with a density range of ...


I use Sandy King's pyrocat recipe and FP4.



It should be mentioned that by using an staining developer (pyrocat...) you may get a dual purpose negative that is easy to print both with regular silver paper and for alternative.

The stain is more opaque to UV than to visible light, so the negative will effectively show the additional top density and contrast under UV.

By playing with the pyro formulations you may adjust the density proportion than comes from the silver grains vs the one comming from the stain that's scaially opaque for UV, obtaining a negative that suits well both the silver paper printing and the alternative under UV. To me this is the particular nice advantage of pyro. Of course pyro chem is less safe than D-76 so, as always...