PLATINUM AND PALLADIUM

Valerie Wheeler
JUDY
Platinum-palladium print
Class of Spring '07

THE AMMONIUM METHOD

The traditional method of hand coated platinum-palladium printing, which has been in use for over a century, uses an aqueous solution of ferric oxalate and potassium tetrachloroplatinate (II). Dr. Mike Ware points out in his essay The Platino-Palladiotype Process* the many problems and limitations inherent in this method. The achievement of an entirely new and improved method of platinum-palladium printing is an historic development for which its inventors, Prof. Pradip Malde and Dr.Ware, deserve enormous credit.

After years of experimentation with potassium and many other salts, Prof. Malde and Dr. Ware found that ammonium salts had three advantages: ammonium was more water soluble thus rendering a more concentrated solution (making double coating unnecessary); ammonium was more hygroscopic, yielding a print-out medium with much finer grained, longer ranged tonalities; and ferric ammonium oxalate could replace the notoriously unreliable ferric oxalate which has always caused problems for platinum-palladium printers.

The "Ammonium Method" as it is sometimes called is used exclusively in ART 162. It allows for the precise control of the humidity level within the coated paper, through the use of an inexpensive, easy to make hydration chamber. The Platinum-Palladium Hydration Characteristics chart shows the most significant variables achieved with this control. Perhaps the most important of these is the print-out factor. Like silver chloride printing-out paper, the self masking nature of the image formation leaves room for shadow detail even as highlight densities are exposed, yielding an image of greater depth and subtlety. It is also less expensive because printing by inspection eliminates the need for test strips. And contrast grading with restrainers such as potassium chlorate or ammonium dichromate, which degrade image quality by simply truncating the tonal scale, also becomes unnecessary.

Prof. Malde and Dr. Ware invented the coating rod now marketed as the "Puddle Pusher." They introduced the use of a moisture barrier in the contact frame, the use of the surfactant Tween 20, the use of EDTA - a more effective and less toxic clearing bath, and the use of Kodak Hypo-Clearing Agent in the processing sequence to aid removal of ferric salts from the paper.

Dr. Ware's essay The Eighth Metal - the Rise of the Platinotype Process is an excellent historical overview of the medium.

PRACTICAL INSTRUCTIONS

Mike Ware's "Platino-Palladiotype" Printing Instructions and Pradip Malde's Platinum-Palladium Printing Instructions should be carefully reviewed.

The Abbreviated Platinum-Palladium Instructions page and the Platinum-Palladium Print Data Sheet should be downloaded and used while printing.

Palladium + Gold
Palladium and gold chloride can be combined to make a print with interesting variations in color, determined by the amount of gold and the amount of hydration introduced. A 3% gold chloride solution is added to palladium coating solution, starting with/ 1 drop per 4x5" coating (.4 - .6 ml.) More drops will yield a more intense color shift.

* The correct name for a print made entirely of platinum is "platinum print" or "platinotype," while "palladium print" or "palladiotype" refers to a print made entirely of palladium. For reasons discussed later most practitioners use a combination of platinum and palladium to make a "platinum-palladium print" or "platino-palladiotype."

home requirements instructions readings galleries