The print tests for the straight palladium prints was most successful, as noted in an earlier post. The 5x7 negatives I am printing from have a density range between log 1.2 to 1.8, and for palladium printing, it is magical. The new order of Revere Platinum paper arrived and has been cut to 7"x9 1/2", ready for coating with palladium. What I am waiting for now is the arrival of 10ml of platinum, which will be used in reduced solution, to be added to the palladium/oxalate mixture, and that will render the final print a platinum/palladium print. For me, the grail of photographic printing.
I am going the way of Dick Arentz and Richard Sullivan who have come up with a variation on palladium printing. The historical process of platinum/palladium printing is very similar to the Kallitype process, mixing the iron binder with the noble metal making up the sensitizing solution. For Kallitype the binder is a 20% solution of ferric oxalate. In palladium printing the same iron binder of ferric oxalate is used, at 27%. There is also a second ferric oxalate solution (27%) in palladium printing, this oxalate solution has potassium chlorate mixed in, and that becomes the contrast control part of the formula, or Part B of the A:B:C parts of palladium printing. Part C is of course the noble metal; palladium, platinum or platinum/palladium. Both intermix quite seamlessly with each other.
Platinum leaves a very black and white image, deep rich blacks and crisp whites, if done right. Platinum has a shorter printing scale than palladium, and is a bit less sensitive. Palladium is very forgiving and can handle negatives that might print on a silver gelatin paper, as well as negatives up to 1.8 density range. The print time would change. Palladium leaves a warm toned image for the most part, and like the Kallitype, the image color can be altered by the developer used. The traditional developer for platinum/palladium is potassium oxalate, but being that chemistry tends to be a bit toxic with precautions offered for its use, other developers have become popular. Potassium oxalate leaves the traditional warm brown color to a palladium print. I use ammonium citrate as a developer, which is less toxic and leaves a more neutral black tone, although still a warm toned image.
The new method of palladium printing mentioned above is referred to as a double sodium formula, or Na2 method, likely because the platinum is used as the contrast control, replacing the old Part B (chelated oxalate). The platinum is sodium based, not potassium based. The historical platinum used for printing is a 20% solution of potassium chloroplatinite; palladium is 15% solution of sodium chloropalladite. The new formula uses sodium chloroplatinate in diluted solutions, added to the palladium/oxalate mixture before printing.
The advantages to this method of palladium printing is that the chelated oxalate used as the contrast control caused a reticulation in the image. A sort of breaking up of the image that mimics 'grain', which increased with the increase in its use in the mixture. The platinum addition keeps any reticulation from occurring, as well as helps separate tonal values and adds a depth to the image. One other very helpful use of the platinum is that the more light you add to palladium, an effect referred to as 'bronzing' occurs, mostly in the blacks and deeper shadow areas, whereas the black tends to begin to show a sort of hazy covering, something like solarization in a subtle form. The platinum keeps this from happening, turning those areas a deep black, as platinum tends to do.
All of which adds up to the simple fact that regardless which base variation of platinum used, the print will be a platinum/palladium print. The dilution part of this is through the dilution of the platinum, beginning with the original 20% solution as it arrives. Two drops of that in a 5x7 print mixture would be for a very thin, flat negative to boost it enough to print well. A 10% solution would be used for a bit contrastier negative, 5% solution for a more contrasty negative still, and 2 drops of a 2.5% solution is to be added to the palladium mixture for a negative in the 1.5 to 1.8 range, which is what I am printing with.
As for affordability, this is far cheaper than imagined. 10ml of sodium chloroplatinate costs $99. 1 ml of that will make 8ml of 2.5% platinum solution, which is what I will be using. 2 drops per print, of 8 ml of solution, which converts (very loosely) to a lot of printing. 1 ml is approximately 20 drops, times 8ml, which comes out to about eighty prints for that original 1ml. Take that times ten, and I can print for a number of years with that original bottle.
The printing of this new portfolio begins as soon as the platinum arrives, and the sun shines. I will of course post images of the prints as I make them. That will satisfy the momentum I had hoped would be evident by this time. As all good photographers know, patience is key to success.
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