IDK why, but the NaBr is still high to me, but again, I may be wrong here. I also know that a carbonate series in the developer gives a contrast (gamma) series in the 3 layers. It is a matter of buffer capacity in the bottom layer making the cyan drop off faster. I seem to remember more carbonate than that. I'll have to test one of my patents, but IIRC, the carbonate in C-22 and C-41 were almost identical.