The standard paper developers I use most (I'm thinking MQ/PQ neutral tone like D-72 and ID-62) with modern neutral-tone papers (the ones I use regularly) really only change effective paper speed with extended developing time. I've not observed a true increase in contrast with the papers I use when developing longer. So, the only use extended development has in this case is to tweak print exposure a bit. Helpful when small changes are needed and manipulations are complicated and already worked out. To get more contrast, one needs to switch developers or alter the developer one is using. I have sodium carbonate, potassium bromide and BTA on hand to do just that, but I'd not be able to determine what to add or how much to try from viewing a test strip. Sometimes the carbonate/BTA combination added to a developer makes a real difference.
With warm-tone papers, developing time affects image tone, so those changes could, indeed, be estimated from the image tone of a test strip. I don't use warm-tone papers or developers, so that kind of adjustment doesn't concern me.
I haven't printed with Ansco 130 or other Glycin paper developers for a while, but I can't really see them affecting contrast much with extended development on, say, Ilford Multigrade Classic or Bergger NB. If I'm wrong here, and someone can document the effect convincingly, I would likely try them out again. I've never used amidol developers; maybe they work differently, especially with contact papers.
I'm pretty happy with my roughly 50% average when printing; half of the paper I use ends up in the trash, the other half is keeper prints.
Best,
Doremus
The only way I have found that an incremental test strip can provide accurate information is with a continuous exposure, the card being moved every set increment with an audible timer.
No other method accounts for the bulb or tube warm up at the start of each exposure and cool down at the end. LED heads may be different. I have no experience with those.
I have another secret tool : the little toaster oven I dry my test strips in. DMax can be dramatically increased just by leaving the strip in there a little too long!
Doremus - if you need "documentation", that is what I call, "the proof is in the pudding". I've got hundred of prints that prove MGWT especially, but also Berrger NB, and numerous other papers, can in fact be contrast controlled to a distinct extent by length of time in 130. I prove that to myself every single printing session. But if you want some web link or silly video, or 1939 darkroom chemistry manual affirming that, well... don't expect me to waste my time on that kind of fishing expedition.
That also worked especially well with the old premium graded papers like Oriental Seagull and Brilliant Bromide. But it didn't have similar punch with more garden variety papers like MG IV, which bottomed out pretty fast.
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