View Full Version : Potassium Oxalate, Green Crystals...

Steve Hamley
9-Oct-2011, 12:53

My potassium oxalate developer for platinum/palladium has crystals in the bottom of the bottle, I suspect from getting super concentrated with use from evaporation of the hot liquid, but some are emerald green.

Anyone know what that is? Just dissolve in hot distilled, filter, and keep using?

Cheers, Steve

9-Oct-2011, 20:15
My Potassium oxalate was the exact same way -- it had sat for 3 or so years. Finally got back to platinum/palladium printing this past week. I just sat the whole bottle in hot water and the crystals melted...and the prints look fine. I did toss in some more distilled water as I have lost volume due to evaporation.

keith schreiber
10-Oct-2011, 15:21
Hi Steve,

Way back in the late '90s I posed the same question on the old alt-process email list. Mike Ware replied that green crystals indicated the presence of chromium. This made sense at the time since I was then using sodium dichromate added to the potassium oxalate for contrast control.

Now I'm not so sure since I abandoned that method some 10 years ago, but still find those green crystals in my developer occasionally. I simply filter them out (or decant into another container), keep the bottle topped off with fresh potassium oxalate, and proceed from there.

Those crystals are kinda beautiful, aren't they!?

~ Keith