Normally, the NA2 method uses only Palladium salts. NA2 is actually Sodium Chloroplatinate - it contains platinum - so you generally don't need to use pure platinum. That's good because the NA2 material is expensive, and the process is economically appealing only if it offsets the need for both the Ferric Oxalate No.2 AND platinum.
I use equal quantities of Ferric Oxalate No 1 and palladium - in my case, 6 drops of each per 4x5 print. The contrast ratios that I use are listed in the table.
This table quantifies contrast via contrast ratios. I don't have any way to measure contrast ratio, but I find that the generic "more contrasty" or "less contrasty" combined with trial and error works reasonably well.
Last edited by Monophoto; 03-24-2009 at 07:25 PM. Click to view previous post history.