pushing TMY one stop with HC110

Over the last months I have successfully standardized on HC110 as an easy-to-use one-shot developer for TMY, TX, and Bergger Pancro 400.

My time for TMY at ISO 320 is 6 minutes at 20 C as recommended by the massive development chart.

Now,for a project, I would like to shoot this film at ISO 800. But when I go to the massive development chart, I am confronted with this mystery:

Kodak TMax 400 HC-110 B 640 7 7 7 20C [notes]
Kodak TMax 400 HC-110 B 800 5.5 5.5 5.25 20C [notes]
Kodak TMax 400 HC-110 B 1600 7.5 7.5 7.5 20C [notes]
Kodak TMax 400 HC-110 B 3200 9.5 9.5 9.5 20C [notes]

As you can see, the time for 640 calls for a bump of 1 minute to 7 minutes--which kind of makes sense. 1600 and 3200 also call for time bumps. But 800 calls for less time, 5.25 minutes for sheet, which seems bizarre to me.

Does anyone have a an explanation for this? Better yet, does anyone have a good starting time for this film at 800 ISO in any dilution of HC 110? Thanks for any help/

Bill

Information on the MDC, while useful, has not been subject to the rigorous testing that the manufacturers use to determine development time data. Given the near-infinite variables involved, that should be no surprise. Nor should we be surprised by anomalies like you've posted. Different people, different methods, different ideas about what's 'good' or 'good enough'. Especially when pushing/pulling.
The answer: Run your own tests!
The traditional rule of thumb for pushing one stop is to increase development time 50% from normal. I'd start with that and see what kind of negative you get; make a proper proof. Adjust from there.

Since you already use 6 min for normal use at 320, I'd recommend trying 8 min for ASA 800. That should get you into the ballpark at least. But hopefully your reason for using 6 min to begin with is based upon testing and printing, and not just
because the Massive Chart seems to recommend that.

Thanks Mark and Drew. I assumed that there would be some variability in the MDC, but this seemed like a pretty significant outlier. I have also seen sources that said you didn't need to make any development adjustment with TMY with HC110 for ISO 400-800, which I also found mystifying. Drew's recommendation is helpful. Thanks again to you both.

I didn't want to complicate anything. If you just want your standard gradiant (gamma), shooting at 800 and developing your normal time would be fine. But
doing so, you're losing a zone of deep shadow value regardless. Sometimes that can lead to a deep blocked-out graphic look in the shadows. I've done it on purpose a few times, but then I increased the development time to get especially rich midtone gradation, and not because the neg would be difficult to print otherwise. So it all depends what you are after. Low contrast scenes will obviously benefit from longer dev. I experimented with 35mm TMZ recently, which
might be marketed as a 3200 speed film; but even their own tech sheet calls it actually 1000. I shot it at 800. But for me at least, shooting TMY at 800 would have given me better results than TMZ anyway. So one more tidbit about potential low-light applications.

That's helpful, Drew -- thanks. I am thinking now that I may start with a little time boost, but not to the full 8 minutes and adjust from there. Thanks again. Bill

If this helps I just pushed a sheet of tmax 100 one stop in solution B at 20c for 8 minutes and am happy with the results.

This was 2 stops at 10 minutes.
Attachment 180386
Just a crop shot on my cell but I imagine it gives you an idea.

That is helpful - thanks.