The platinum/palladium printing process was invented by William Willis in the 1870's and patented commercially in 1879. By the turn of the century platinum prints were very popular, valued for their beauty and their intrinsic permanence. Platinum and palladium are two of the most inert elements (noble metals) in existence which contributes to the archival stability of platinum/palladium prints. With the onset of World War I, platinum family metals were hard to come by in the US and platinum papers had to be imported from Europe. By 1941, commercially produced platinum papers were no longer available. Contemporary print makers who desire the unique and beautiful qualities of this process create their own printing paper by mixing the light-sensitive chemicals and coating paper by hand. Many print makers thrive by working this way, gaining both technical control and personal satisfaction from this hand-made approach to photographic print making. The process involves mixing small quantities of a sensitizer solution (ferric oxalate) with solutions containing the platinum and/or palladium metals. This mixture is then applied to fine rag paper or other media, using either a brush or a glass rod which evenly spreads the solution across the paper. The platinum mixture is only sensitive to ultraviolet light and is therefore a contact printing process (the negative must be the same size as the desired print). The platinum and palladium becomes embedded within the fibers of the paper which results in an image that is as permanent as the paper itself.
Combined Gum Bichromate & Platinum/Palladium
The gum bichromate process uses watercolor pigments suspended in gum arabic mixed with dichromate to form an image. The contact print is made under ultraviolet light which reacts with the dichromate to harden the gum/pigment mixture resulting in an image whose color is determined by the pigment or pigments used. Straight gum prints are typically made by printing several layers in registration to build up overall density and color. I use gum as a way to modify and enhance a platinum/palladium print and rarely make straight gums. This technique was used by many of the pictorialists in the early 20th century including Edward Steichen, Alfred Steiglitz and Alvin Langdon Coburn. Pond Moonlight is a gum-platinum print by Edward Steichen that sold for $2.9M in 2006, at the time the highest price paid for a photograph at auction. At the time the aesthetic for the gum-platinum print was to add a decidedly painterly and somewhat gritty look. My approach is different in that my intent is for the gum to blend smoothly and seamlessly with the underlying platinum/palladium print and preserve it's characteristic tonal smoothness. The gum also adds depth to the shadows and the colors chosen can have a significant affect on the mood of the print. After making the platinum print, I re-size the paper with gelatin, coat the paper with the gum bichromate mixture and expose the print to UV light with the same negative in registration with the platinum image. Usually, I only add one layer of gum occasionally I add two or more.
Wet Plate Collodion
I first learned the wet plate collodion process in 2004 from Will Dunniway. Since that time, there has been an explosion in interest in this process. The web and YouTube have lots of information about the process, so I'm not going to go into the process details here. I encourage you to browse if you'd like to learn more. I had originally planned to use the process to make glass plate negatives for my large view cameras, but became much more interested in positives - ambrotypes on glass and tintypes on aluminum. Below is a video my daughter and I put together showing the process in action.