The formation of grain in making AgX is a very "delicate" mechanism. Several very smart people have spent their entire professional careers studying the crystal growth mechanism. They have attempted to explain all the factors to me but I don't pretend to have a full understanding. I understand the results but not how to get there. Tech Pan x415 is a very fine grain emulsion that has grains that are all about the same size. Several steps are taken to deliver the desired grain. This provided a versatile film that could be developed to a wide range of contrasts. We enjoyed formulating Technidol developers and working out the difficulties in providing 35mm, 120, and sheet film. Lots of challenges but enjoyable. Those were the good old days.