Creating suitable alt-process negatives with Pyrocat-HD

[ProfessorC1983]

I've been reading up on the effects of staining developers, specifically Pyrocat-HD. Sandy King's article (http://www.sandykingphotography.com/resources/technical-writing/pyro-staining-developers) points out that because Pyrocat-HD's brown stain blocks more UV than blue light, negatives present an effectively higher contrast index for alt processes.

He even points out that it may be possible to create dual-purpose negatives (especially with FP4+ at a 1:1:100 dilution, as per Figure 7) that present such a different effective CI for UV vs. visual light that they could print well with some alt processes as well as silver gelatin (presumably grade 0/00 paper). Is anyone doing this? Is it a worthwhile endeavor?

What I don't quite understand is how to derive a number for the "UV CI" for a particular film/developer/routine based on the traditional number produced by film tests (slope of the "straight line" part of the curve, i.e. ΔlogD / ΔlogH) as the graphs on the King article aren't super clear. Is this even possible without a UV densitometer?

My ultimate goal is to derive a set of test results that correlate CI, DR, and exposure scale for a given process and film/developer combo so I can have an easy reference to answer questions like "how long should I develop this roll of FP4+ (assuming a given SBR) in Pyrocat to make suitable negatives for cyanotype/kallitype/salt?" and/or "what process would be best suited for this Pyro negative that ended up at a given CI (or DR)?"

(Another wrinkle is that I print with a condenser enlarger so I know I need to take the Callier effect into account, which is absent from a lot of the literature on alt because it all assumes contact printing... but that may be a problem for another day.)

Feel free to tell me to RTFM here -- I just don't quite know where the "M" is!

 

[Peter Schrager]

many alt processes do not need an extremely dense negative. you can 1:1:100 and create negatives that are dual purpose.
I use it at 2:2:100 for my POP prints. these will not print on an enlarger.
best is to start making some negatives and see what develops!!
have fun!
best, Peter

 

[juan]

Without a densitometer that reads UV, you’ll have to experiment - a lot.
I use the BTZS system and a minimal agitation scheme with diluted developer, so I’m not sure my specifics would help you. Keep notes.

 

[J 3]

many alt processes do not need an extremely dense negative. you can 1:1:100 and create negatives that are dual purpose.
I use it at 2:2:100 for my POP prints. these will not print on an enlarger.
best is to start making some negatives and see what develops!!
have fun!
best, Peter

This is an excellent technique if you like printing in multiple media. One thing to note the two staining developers are not identical in this regard. The yellow-green stain blocks a lot more blue and UV light than does the mild brown stain. Salt in particular wants a dmax in UV as you can give it because of self shadowing and limited contrast controls. Getting a negative that will print on silver gelatin and a salt print would be the tricky combo.