This technique was first developed in 1873 in the era before photographic enlargers. A high quality rag paper is hand coated by the artist with a solution of platinum and palladium salts in the presence of a ferric sensitizing agent. A negative is placed in contact over the sensitized paper under glass and exposed to ultra violet light (originally sunlight) for a period of minutes. After processing, the resulting image is then physically part of the paper fibers and will last as long as the paper does.
Inherent to this technique are many differences from both silver gelatin and inkjet printing. The tonal gradations are very smooth and long scale, and the color is a pleasing rich brown. Just the choice of paper can have a major impact on the feel of an individual image. While this is a difficult process to master, I have enjoyed the hands-on character of this method. Each print, even from the same negative, ends up having a uniquely individual character due to the many variables involved. There is absolutely no doubt that platinum / palladium prints last well over a century in the real world. This and the unique look of a print that could have been made in the 1800s attract me to this process.
I taught a class in Alternative Processes at Palomar College last summer. Please note that some of these are actually larger than life size when zooming in. Most are from 4 x 5 inch negatives and as the process requires, that is the size of the print.
© Will Gibson