AOS Artist Directory |
Photographic platinum/palladium prints
Location @ AOS:
Arlington Town Hall (730 Mass Ave)
Photographic printing using platinum salts, palladium salts or a mixture of the two, is one of the oldest methods of reproducing a photographic image. Platinum prints are capable of producing a more subtle gradation of greys than other black and white photographic processes and are best used for images suitable to this palette.
Platinum and palladium salts are not particularly light sensitive but the process can be enhanced through the use of a sensitizer, usually ferric oxalate. The platinum and palladium are mixed with the sensitizer and brushed onto a sheet of pre-sized artist's paper creating the photo-sensitive surface.
Platinum printing is a contact process meaning that the negative must be the same size as the finished print. A large negative can be created in one of three different ways. 1) Use a large camera. There are cameras that produce a 5 x 7 inch, 8x10 inch or larger negatives suitable for this process. 2) Produce an enlarged negative in the darkroom, using a photographic enlarger. 3) Scan the original negative, enlarge it using Photoshop and print it on transparency material using a photo quality ink jet printer. Method 3 can be used to create a large negative from a digital original.
The platinum sensitizer is not particularly sensitive to visible light which means that the creation of the photo-sensitive paper can be done in dim light. The negative is brought into tight contact with the paper, using a pressure or vacuum contact frame, and exposed to ultraviolet light for 4-10 minutes. After exposure, a faint image can be seen on the paper which then must be developed in a sodium oxalate solution. After development, the unreduced metal salts are removed in a bath containing sodium sulfite and EDTA. Correctly washed platinum prints are very stable and will last for hundreds of years.