Quote Originally Posted by David Lyga View Post
First: What is the precise role of bromide in Farmer's Reducer?
I think you mean re-halogenating bleaches. Potassium bromide is used so that when the silver is oxidized it is converted to silver halide again. Such a bleach may be used in connection with an intensifier.

Ag0 - electron --> Ag+ + Br- --> AgBr