I’m sharing these two images as demonstration of the effect of NA2 on contrast, and how a little goes a VERY long way. NA2 is shorthand for Sodium Platinum, a restrainer/contrast boosting agent. It affects the color tone of the print as well as the contrast, giving an overall more neutral/cold color to an otherwise warm chocolatey brown palladium print. What many beginning pt/pd printers don’t get is how little NA2 you need to effect contrast and tone shifts in your prints. This post illustrates that impact.
NA2 is only useable with pure palladium prints- if you want to include platinum as a blend, or make a pure platinum print, you have to use dichromate or something else as a contrast booster because the platinum in the NA2 binds with the platinum in the solution and primarily affects the highlights, not actually increasing overall contrast, and the net effect is flushing expensive platinum down the drain.
Both prints were made with 9 drops palladium/9 drops Ferric Oxalate, on Hahnemuhle Platinum Rag paper, exposed for 15 minutes. Image size is 8×10 inches. The print on the left had no NA2. The print on the right had 1 drop of 5% NA2 added. Obviously this is way too powerful. I’m going to re-print trying a 1% and a 2.5% concentration to see which gets me where I want (still retaining detail in the Washington Monument, but brighter highlights and more tonal separation in the trees on the left).
Apologies for the quality of the reproduction photo- it was shot on my phone and collaged using a phone app, but it does reasonably accurately replicate the contrast differences between the prints. The tonal shift is less obvious because the phone is not so good at color temperature correction.