I have a question. I know that sulfide and thiourea toners will tone silver bromide, regardless of whether it's exposed. What other toners behave that way? Selenium: if it was KRST, the amm. thiosulfate would dissolve undeveloped AgBr, so not this one, right ? Iron blue toner ( AFC + pot ferri + weak acid )? Copper toner ( copper sulfate + pot ferri + K-citrate or maybe Na-citrate )? Any others? Are there other fogging agents that aren't used as toners?