Since I know others continue to work to find the sweet spot of this film, I thought I'd update my findings:
After a ton of further testing this summer, I have concluded that Double-X doesn't like highly dilute Pyrocat-HD when used with standing development. Any combination of dilution and/or time I tried gave me grainy negs that had a kind of gritty look. I did not try conventional development with Pyrocat-HD at 1:1:100. However, I
did try it with conventional PMK Pyro development and got that same grain/grit look. My working hypothesis is that Double-X doesn't like super dilute developers and/or Pyro-based developers no matter how you process.
So, I tried some other developers and got night and day better results. In order of improving quality:
HC-110B Conventional: 6 1/2 min. 30 sec initial agitation, 5 sec agitation every 30 seconds thereafter
D-23 1+3 Semistand: 1 minute initial agitation, 5 sec agitation at 16 min, pull at 30 min
D-76 1+1 Conventional: 7 1/2 min total, 30 seconds initial development, 5 seconds agitation every 30 second until 4 min mark then 5 sec every minute until done.
All of these produced sharp, smooth negatives unmatched by either Pyrocat or PMK.
The HC-110B negatives were grainiest, with least tonal smoothness. Not terrible, and certainly better than the Pyro-based developers, but not as good as the other two developers.
Both the D-23 and D-76 developed negatives were excellent, with high acuity and minimal grain. The D-76 negatives are ever so slightly better showing less grain, holding high amounts of detail well, and exhibiting great tonal smoothness. However, the difference, while visible, isn't huge and I'd be comfortable using either of these, the D-23 when I want longer development times for expanded mid-tone contrast, and the D-76 for everything else.
Last year, I also did some testing with super dilute D-23 and semistanding Double-X for 60 minutes: 1+9 + 0.5g/l sodium hydroxide. You get negatives that are super acute, but prounounced grain. If I were to do this again, I'd probably dial back total standing time 10-15 mins. This is a look you either love or hate:
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