Palladium Na2 method
I've managed to finally get some decent prints using the B&S Ferric Oxalate 1 and 2 solutions, and just got their Na2 Kit. But I need some advice as to a starting point. I'm doing my current prints at 1/3 2/3 ratio both for platinum to palladium and the Ferric Oxalate solutions - for 12 drops of palladium what's a good starting point for how many drops of the Na2 solution? (there's no indication if the Na2 is 5, 10 or 20% concentration)
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.
NA2 is quite potent, so I would start off with "less is more" until you get your process nailed down. Let's put it this way - I only use 1 drop of the stock dilution for an 8x10 (roughly 12-14 drops Palladium and 12-14 drops FeOx) when dealing with a fairly flat negative. YMMV, so experiment.
If you got the same kit I did you have 20% solution. You need to make other dilutions from your "stock", to give you a range of contrasts.
I mixed 4 parts H2O to 4 parts Na2 for 10%
6 parts H2O to 2 parts Na2 for 5%
7 parts H2O to 1 part Na2 for 2.5%
I've attached a scan of a chart I made for myself from info in Christina Anderson's book "Alternative Processes Condensed".
Hope this gives you a starting point. Post some prints when you have some.
Tim, here is an excellent reference by Dick Arentz, http://www.dickarentz.com/na2.html .... I have done the step tablet test using the chart and the numbers are rock solid ...