The process for making platinum prints was invented in 1873 by William Willis. The process depends on the light sensitivity of iron salts to create an image. Chemical reactions exploited during developing, however, dissolve out the iron salts and replace them with platinum.
Platinum palladium photographs are among the most permanent graphic image in any medium. This process involves mixing small amounts of platinum and palladium with a light sensitive solution containing ferric oxalate. This mixture can then be spread onto the surface and is left to dry. After the emulsion is dried, the paper is placed in contact with a negative the same size as the final print and is exposed to ultra-violet light or sun light. Finally the exposed print is processed. Then it is cleared by washing out the ferric oxalate with several successive baths of hydrochloric acid. It’s finished by washing in water and dried.
Wet-Plate Collodion Process
Wet-plate collodion is a captivating process with a mysterious allure. Like the photographers of the 1850s, I use hand-poured chemistry that I mix myself according to original recipes, period brass lenses, and wooden view cameras to expose positive images directly onto black enamel aluminum plate.
The process involved adding a soluble iodide to a solution of collodion (cellulose nitrate) and coating a plate with the mixture. In the darkroom the plate was immersed in a solution of silver nitrate to form silver iodide. The plate, still wet, was exposed in the camera. It is then developed by pouring a solution of pyrogallic acid over it then fixed in a tray of potassium cyanide. The plate is then washed in a tray with running water for 30 minutes. Each plate is one-of-a-kind and varnished with a mixture of gum sandarac and oil of lavender.