Platinum/Palladium NA2 method - I'm so confused?

[Dan Dozer]

Sometimes I wish I would have paid more attention in Chemistry Class.

So - I'm starting to get back into Platinum/Palladium printing after a break of about 3 years or more. I had gotten pretty heavy into the NA2 method getting my chemicals from Bostick and Sullivan. I'm starting to run a little low on both metal salts so I got on their website. WOW - what a shock on the increases in prices! After I got over that I started looking at their powders instead of their solutions and what they sell now isn't the same as back then. Perhaps the chemicals are pretty much the same, but I don't know. I've also been to the Artcraft website to see what they have which is where it gets really confusing.

Artcraft carries Potassium Hexachloropalladate and Potassium Tetrachloropalladate (II). Does anyone know if they are the same as it applies to palladium printing? I don't know the difference between the two. To make it more confusing, B&S sells Palladium Chloride. Is that just the trade name for chloropalladate?

Now on to Platinum. Artcraft carries Potassium Tetrachloroplatinate II (with an A). B&S carries Potassium Chloroplatinite (with an I). Now I seem to remember way back to high school chemistry that the "A"s and "I"s aren't the same thing.

Going back to the chemicals that I was using before (that I got from B&S) - I was using Sodium Chloropalladite and Sodium Chloroplatinate. B&S doesn't sell the sodiums anymore.

Does anyone out there know what I should be getting for the NA2 process?

 

[Ian Leake]

The so called "NA2 process" is simply a variant of the traditional pt/pd process - albeit a very useful one. "NA2" itself (also known as "Sodium Platinum") is just another restrainer like sodium chlorate and the dichromates. It's a high quality restrainer, but it only works for the palladium salt. You include it in the coating.

I don't think I've seen the actual chemical formula for "NA2" nor the strength of solution that's included in the B&S product. The simplest and most reliable source for this chemical is B&S themselves.

The B&S products that you will need for "NA2" are:

1) Ferric Oxalate #1 - which is Ferric Oxalate without any added restrainer
2) Palladium Solution #3 - which is Sodium Chloropalladite (not sure of the concentration) - I'll try to find the specific formula when I get home

I have found Artcraft to be really good, but you have to know what you're buying and also the concentration of the solutions you'll be making. In the past that's where I've sourced the chemicals for the Malde-Ware process. But I wouldn't source traditional process materials there simply because the B&S products are high quality and known to work together.

If you're determined to find an alternative supplier for traditional platinum/palladium then you should expect to have to experiment a bit (e.g. to optimise the concentration of your sensitiser solutions). I would also use a different restrainer such as potassium dichromate - i.e. one that is well understood and easy to buy. That would at least take one variable out of your experimentation.

I realise that I haven't exactly answered your question, but I hope it's useful nonetheless.

Ian.

 

[Vaughn]

The so called "NA2 process" is simply a variant of the traditional pt/pd process - albeit a very useful one. "NA2" itself (also known as "Sodium Platinum") is just another restrainer like sodium chlorate and the dichromates. It's a high quality restrainer, but it only works for the palladium salt. You include it in the coating.
...

Correct, but I have pictured Na2 as more of an accelarator than a restrainer. Somewhere I have a paper on its action in the printing process, I'll have to track it down again. The main advantage of Na2 is that higher contrast can be achieved without the graininess that occurs when using the Potassium chlorate in larger amounts.

 

[Dan Dozer]

Correct, but I have pictured Na2 as more of an accelarator than a restrainer. Somewhere I have a paper on its action in the printing process, I'll have to track it down again. The main advantage of Na2 is that higher contrast can be achieved without the graininess that occurs when using the Potassium chlorate in larger amounts.

This is what I understand the advantage of the NA2 method is as well. You supposedly get better control of contrast, may have less grainyness, and can also work with lower contrast negatives. This is important to me as most of my work is with silver, and having high contrast negatives (the normal thinking with standard Pt/PD printing) is obviously a challenge with silver printing.

 

[Ian Leake]

I use "restrainer" in the sense that it restrains the chemical reaction that frees the palladium from the palladium salt. Because less palladium salt is converted into palladium, this increases the contrast of the sensitiser, which means you can match your print to a less dense negative.

It's a term I picked up from Dick Arentz, I think. It's conceptually similar to the restrainer in a silver gelatin emulsion (although chemically different).

NA2 gives lovely smooth highlights; potassium chlorate quickly ruins them if you use too much. Dichromates also give lovely smooth highlights, and they also work for platinum which is important if you want to work with platinum.

 

[Vaughn]

This is what I understand the advantage of the NA2 method is as well. You supposedly get better control of contrast, may have less grainyness, and can also work with lower contrast negatives. This is important to me as most of my work is with silver, and having high contrast negatives (the normal thinking with standard Pt/PD printing) is obviously a challenge with silver printing.

I do very little silver gelatin printing these days, but occasionally will make palladium/Na2 prints with some older negs (esp 120 film) processed for silver printing. Generally though, I expose and develop negs for a particular process -- this allows me to use a particular process' characteristics without having to push the process to its limits...I try to use no contrast agents for my platinum/palladium prints. This means that I might exposed a couple sheets of film of the same image...then process them differently...pushing the contrast even higher for carbon printing than I would for platinum/palladium printing.