I was wondering what the role of disodium phosphate is in ferricyanide based bleaches? Every ferricyanide recipe I've seen has it... what can I substitute it with? (I live in Australia, but vanbar do not stock it, but they effin stock potassium dichromate! otherwise it'd be $3 for 500 grams like everything else from them)... Sigma Chemicals (Australia) want $50 for 500 grams and $80 shipping.. vanbar get a lot of their chemicals from here.. what a joke.. Anyway, so I need to replace it. Vanbar sell EDTA tetrasodium salt and EDTA acid, not Ammonium Ferric EDTA, they also sell Ferric Ammonia Citrate, and Ferric Ammoniun Citrate, but I dont have a recipe for bleach from these. I'm left with Potassium Dichromate bleach (no way), and Copper Sulphate bleach (Acceptable as last result, but not keen on the alleged colour shifts compared to ferricyanide and edta bleaches).