Previously I have used Bostick and Sullivan premixed solutions in little brown bottles for Pt/Pd printing, Na2 method. The ferric oxalate solution from them was slightly coloured, but clear. I ordered powdered chemicals from JD Photochem this time. I have just mixed up 15 grams of Ferric Oxalate with 1 gram of Oxalic Acid and 55 ml of water - as per recipe in CZ Anderson's book "Alternative Processes Condensed". The FO powder is a very pretty yellow colour, and the "solution" is also a very pretty yellow colour. It looks like paint. I don't think any of the powder dissolved - and suspect it will all settle out. Does it need to be heated? Have I got the wrong formula? Thanks in advance for your help.