I am thinking of shooting the next Tri-X assignment either at 800 or 1600. This might be pushing it, no pun intended, but I am feeling both experimental and skeptical about it at the same time.
Something is tugging at me to just mix D-23 straight for this and not use BT2B. I have been reading mixed opinions about D-23 being used as a push developer. I have exposed Kentmere 400 at 800 using undiluted D-23 from last April's assignment "Time". That scene had a wide tone range; highlights did blow out some.
From this:
https://www.photrio.com/forum/threads/msa-o-n-april-2024-time.205906/post-2785191
"Film developed in D23 undiluted for 11 minutes and 15 seconds at 70F/21C"
I started using BT2B a few weeks after that assignment. I bet BT2B would have helped out with the highlights in that scene.
Without any testing and thinking aloud in my head on how to translate that April's assignment data of undiluted D-23 time to BT2B:
Tri-X 400 at 800 - Bath A = (5 * 1.4) = 7m
Tri-X 400 at 1600 - Bath A - (5 * 1.4 * 1.4) = 9.8 rounded to 10m
Using (5 * 2.8) gives 14m which would be too long. Depending on how hot the highlights are; if any bright lights inside of a building or windows showing, it may be a good idea to either slightly lessen development in bath A or use the calculated development time I had just made and then use a lesser amount of metaborate in bath B, something like 7 grams per liter. Just enough to build up the shadows a bit more and not touch the highlights. Because of a loss of speed the shadows could end up being vacant from such underexposure and over development.
I do see a possible issue with increased grain using BT2B for pushing. Undiluted D-23 would be softer working and may be the better option. Kentmere does have more of a grain structure than Tri-X so my guess is that Tri-X should be all right with a slight nudge to 800 without a hitch. The developing time would be slightly different due to the 1 gram extra of Metol and 20 grams of extra sulfite. If Kentmere was 11:15, from that past assignment, then Tri-X might be somewhat close.
I just went to the MDC site and the chart shows "11 minutes" for Tri-X at 800 for D-23 undiluted, 20 minutes at 1600 for D-23 1:1. All at 68F/20C. I used 70F/21C. Seeing this I probably could have backed off a little bit on the development for that past assignment. 10:00 might had been better instead of 11:15.
In the past I used D-76, T-Max and HC-110 for pushing films. I could make D-76 but I currently do not have any borax and boric acid on hand to complete the mix. These chemicals would take a little while to get. I looked around to see if I could use a lesser amount of metaborate, mixed with something else, instead of the borax but came to the idea that it may not be worth while doing that.