Quote Originally Posted by Michael R 1974 View Post
Solvent action comes from the sulfite, but the amount of time the sulfite has to act can be as important as the concentration. Assume for a moment there was no part B in OP's developer. Reducing the amount of sulfite also reduces the pH, which, all things being equal, increases development time. (...)
That's correct: in a metol-only developer, sulfite acts as solvent AND as activator (pH).
But in a two-bath developer like TD-201, temperature or time has little or no effect, at least within the 20-22C range. That's a difference between two-bath developers and D-23 vs. D-25 and that's why I asked how to increase activity chemically.

Quote Originally Posted by Michael R 1974 View Post
This is one of the reasons I initially asked OP how he knows TD-201 isn't sharp.
I wonder how to improve sharpness, I did'nt say it's an unsharp developer.