It is more common to measure emulsions in terms of vAg and not pAg. Using that reference, a vAg of much over 100 mv is problematic. At 100 mv, the pAg would be in the range of 8.+ for NaBr at 40 deg C. On that same scale a vAg of -50 mv would be a pAg of about 10.+. Generally, in the range of 100 mv or higher, emulsions tend to fog quickly whereas below that, emulsions keep better. Halide excess is the norm with Silver Halides made in Gelatin.