We like to catalog and categorize things to make general rules about how to change things. We have solvent developers, non-solvent developers, high acutance developers, and on and on. With a good lens sharply focussed on the subject of interest, why should we not be satisfied with what we saw on the ground glass or in the viewfinder? How would you categorize a sulfiteless solution of Phenidone, ascorbic acid and borax in water? I did it to see what would happen. Where's the preservative? How can I have fine grain without a silver halide solvent? Thus far, I have tested only HP5+ and Arista EDU 400, and I have 11x14 prints that show no grain from greater than 6" viewing distance.
Of course, ascorbic acid is an antioxidant. At the pH of borax, one could wait all day and not see any sign of development, but add a pinch of Phenidone and Voila! Is it synergism, or simply rapid regeneration of Phenidone by the ascorbate, or are both the same? Is the ascorbate also a solvent of silver halides? I have read that it is a surface developer which fact makes its grain finer, but it wasn't even a developer until I added the Phenidone. But who cares about all this if it works?
Forgive the ramble.