I'm having conceptual difficulty understanding exactly what effect the "restrainer" (whether potassium chloride or sodium chloroplatinate (Na2) added to the ferric oxalate) has on the contrast of the print. Does more restrainer give the resulting positive print more contrast or less? Does it impact the entire tone curve or just the highlights or shadows? I started out with 50 50 B&S solutions 1 and 2 and changed that to 2/3 1/3 which helped with the grain, but I can't see any difference in the contrast. Thanks for any explanation.