Originally Posted by DrPhil
Ammonium citrate is a "slower" developer, you loose about one stop when using it compared to Pot oxalate. It gives you a more neutral tone than Pot oxalate and like Mateo said, prints developed in it lack the "glow" a well made pt/pd print can exhibit. I like Pot Oxalate as the developer much better than ammoium citrate.
Like Mateo I use HCA. It works and it is cheap, much cheaper than EDTA or citric acid. Anything that dissolves Iron will work fine, I have heard of some people using sprite as CA. the phosphric acid in it is good enough to clear a print.
While the kits are convenient, if you plan to stick with it, buy the bulk materials. There is nothing more maddening than experimenting and running out of solutions. Michael at Artcraft chemicals is selling the Pd at $12/gram and the Pt at $20/gr. If anything you can go with the Pd only and experiment with that before you do the pt/pd print.
With exception of Arentz, I dont know anybody that likes Platinotype better than other papers. Arches Platine, COT320, Even Socorro with an Oxalic acid prebath are far better IMO than Platinotype. I would say instead of ordering a bunch of one paper, order about 2 or 3 sheets of each and try them all, see what works best for you.
If you can, get the Richeson 9010 brush, it will save you a whole bunch of money on coating. Far better than the hake brushes or the puddle pusher.
Good luck, and welcome to the club....