What makes T-MAX Developer unsuitable for sheet film development?

[miha]

T-MAX developer has been considered unsuitable for sheet film development, supposedly because it can cause dichroic fog. It seems to be the only commercial developer with this shortcoming.
What’s especially confusing is that, since the demise of the RS variant and the introduction of the newer T-MAX developer formulation, it still hasn’t been tweaked to make it suitable for all film formats.
What exactly about T-MAX Developer causes problems with sheet film?

 

[Ian C]

I’ve often wondered that myself. Years ago, I had wanted to develop some 4” x 5” and 8” x 10” T-Max film but had no D76 Developer on hand.

I had a fresh bottle of T-Max Developer concentrate. I had read the Kodak warnings against using it for sheet film. I decided to process a single sheet and inspect the results carefully. It was perfect. That was at least as far back as the early-to-mid 1990s. I've continued to use T-Max for sheet films since then. I’ve yet to see dichroic fog (or any other defects) in any T-Max sheet films I’ve tray developed in T-Max Developer at the standard 1 + 4 concentration. I use Kodak’s reuse schedule:

I determine the temperature and use the Kodak temperature/time chart to determine the normal developing time N for the first 1/3rd of the stated capacity. After processing the first 1/3rd of capacity, I pour all the working-strength developer back into its storage bottle to form a uniform mixture.

Then I use N + 1 minutes for the second 1/3rd of capacity. I remix the entire batch as above after processing the second 1/3rd of capacity.

The final third of capacity is developed at N + 2 minutes. Then I discard the exhausted developer.

Did Kodak make some changes to its T-Max emulsion or the formulation of T-Max Developer since the warning was first issued? I don’t know. So long as I get consistently good results with no ill effects, I’ll continue to use it with all my T-Max films, both rolls and sheets.

Note: I have never used the RS version of T-Max Developer.

The capacity with reuse schedule is given on the bottom of page 9 in the following PDF:

https://business.kodakmoments.com/sites/default/files/wysiwyg/pro/chemistry/j86.pdf

 

[Milpool]

What Kodak said about this was that the relatively "open air" situation for sheet film in film holders caused the TMax emulsion to be somewhat prone to dichroic fogging when processed in the regular TMax developer. John Sexton had noticed this during prototype testing in the 1980s and pointed it out to Kodak.

It seems with the more recent iterations of non-RS TMax developer / TMax films this might not be a problem anymore.

You can read more about it in John's newsletter addressing the discontinuation of the RS version:

John Sexton.com - Newsletter - November, 2020

I’ve often wondered that myself. Years ago, I had wanted to develop some 4” x 5” and 8” x 10” T-Max film but had no D76 Developer on hand.

I had a fresh bottle of T-Max Developer concentrate. I had read the Kodak warnings against using it for sheet film. I decided to process a single sheet and inspect the results carefully. It was perfect. That was at least as far back as the early-to-mid 1990s. I've continued to use T-Max for sheet films since then. I’ve yet to see dichroic fog (or any other defects) in any T-Max sheet films I’ve tray developed in T-Max Developer at the standard 1 + 4 concentration. I use Kodak’s reuse schedule:

I determine the temperature and use the Kodak temperature/time chart to determine the normal developing time N for the first 1/3rd of the stated capacity. After processing the first 1/3rd of capacity, I pour all the working-strength developer back into its storage bottle to form a uniform mixture.

Then I use N + 1 minutes for the second 1/3rd of capacity. I remix the entire batch as above after processing the second 1/3rd of capacity.

The final third of capacity is developed at N + 2 minutes. Then I discard the exhausted developer.

Did Kodak make some changes to its T-Max emulsion or the formulation of T-Max Developer since the warning was first issued? I don’t know. So long as I get consistently good results with no ill effects, I’ll continue to use it with all my T-Max films, both rolls and sheets.

Note: I have never used the RS version of T-Max Developer.

The capacity with reuse schedule is given on the bottom of page 9 in the following PDF:

https://business.kodakmoments.com/sites/default/files/wysiwyg/pro/chemistry/j86.pdf

 

[miha]

John Sexton.com - Newsletter - November, 2020

Thanks for the link.