I’m fairly new to PT/PD printing and would like to know the capacities and keeping properties of some of the chemicals used in both coating the paper and developing the print. The two chemicals I’m seeking capacity and keeping property for is ferric oxalate sensitizer and potassium oxalate developer. Besides the numbers of prints that can be coated and processed (square inches) are there things to look for regarding exhaustion of these chemicals and are there steps to be taken (such as filtering) to maintain the solutions? I’ve looked at a great deal of the available literature but most of it is fairly vague on this issue (unlike traditional film processing information). I’ve also noted when watching some of the many YouTube videos that some practitioners are using print developers that appear almost black when poured? Any advice or knowledge you can share would be appreciated. Best regards, Mark Godfrey.