I had some green sludge in my potassium oxalate developer for my pd prints yesterday. Any ideas on what it is? My thought is that it is crystalized pot ox because I had the developer in an open tray for about 4 hours, definitely long enough for H2O to evaporate and the pot ox to leave solution and precipitate.
PO developer returns to a crystal state, not a sludge. There may be some excess palladium metal in the developer which can be removed by filtering through a coffee filter. If you add some more water and heat it up a bit, the PO will go back into solution. If anything remains it might be Pd metal. Then again, I don't know what the quality of your water is.