Palladium photographs

Palladiotype is one of the most noble and expensive processes. Its main features are long tonal scale, especially in the shadows, deep dark values, almost absolute persistence over time: the metallic molecules trapped in the paper will gone only with the paper itself. No risks at all for fading.

The process in brief

In dimmed incandescent light, ferric oxalate (iron) and Palladium (Pd) salts are mixed in equal amount to obtain a sensitizing agent which is used to coat 100% cotton paper with a glass rod.

Once the paper has dried, a photograph negative, which is the same size as the final photograph, is put in contact with the paper and exposed to UV light for varying times depending on the image and the relative humidity which does affect the process.

The right UV exposure time produces the image.  The paper with the image is then placed into bath of (potassium oxalate or ammonium citrate) to finish the developing of the image. Baths with EDTA and/or sodium sulphite allow the removal of the unexposed sensitiser, so clearing the highlights. After final wash in water, the paper is hang on a line and dried.