Typically fine grain is accomplished by more solvent action. This typically means more sodium sulfite. In fact D-76 undiluted is a solvent developer. Diluted, the sodium sulfite concentration is less, so it more a high acutance developer.(posted 8859 days ago)Pick up a copy of "The Film Developing Cookbook" by Steve Anchell. It will teach you all of this, as well as giving you a lot of formulas to try.