I'm making a 20% ferric oxalate solution for kallitypes for the first time. I'm starting with 2-3 year old powder that I bought from B&S. I added 40 ml of distilled water to 10 g of FO powder (which was lime green) and had a lime green suspension. Heating for short 10-20 second bursts in the microwave turned the solution into a clear yellowish-brown. Is this the right colour, or have I cooked the heck out of it?