Sodium chloroplatinate (Na[SUB]2[/SUB]) is used as a contrast agent (more highlight inhibitor) for palladium printing. It works both with Na and Li palladium(II) salts but when I tested it with the ammonium salt (NH[SUB]4[/SUB])[SUB]2[/SUB][PdCl[SUB]4[/SUB]] a precipitate forms instantaneously. I tested Na[SUB]2[/SUB] with a drop of fresh ammonium citrate developer and the same precipitate forms. Ammonium citrate is recommended as a standard developer for the Na[SUB]2 [/SUB]method (even sold as a kit with Na[SUB]2 [/SUB]by B&S). So I am somewhat baffled why it should work with that developer.