Horse Barn: gum Bichromate

This gum print was made from a 9" x 6" B/W negative. The print was exposed 5 times using a different hue/value each time. When I print this one again there are some things that I will do differently, but I think that this one does have a certain charm!

Gum Bichromate: "St. Francis at El Rancho"

This is another of the gum prints that I have been working on. For comparison the original B/W of this is shown near the end of this page. From the original I made a 9" x 7" digital negative using Photoshop and printing it to a transparency using a lazer printer. This print has had four exposures and developments: Yellow, Alizarin, Lamp Black and Charcoal Grey ( all watercolors). The paper is 140lb cold pressed watercolor.

Full Color Bichromate Print

This is a full color Gum Bichromate print that I have been working on for two days. I began with a color digital photo that I resized to 8 X 6 inches. The original photo had been processed in PS CS2 and all of the rest of the prep work was also done in PS CS2. I changed the mode to CMYK and then split the channels. Selecting each of the split channels separately I inverted and rotated each one horizontally. I then had a lazer transparency (B/W) made of each channel. My first exposure was for the Y channel and I used Winsor Newton Aureolin Yellow, after this was developed and dry I printed the Magenta negative using W/N Alizeran Crimson, next was the Cyan negative and I used W/N Thalo Blue and the very last printing was with W/N Lamp Black. All the pigments are watercolors from a tube and were mixed with gum arabic and ammonium dichromate. Each contact print was exposed in the sun for 4-5 min and developed and washed in water. The paper I used was Strathmore 90lb cold pressed watercolor paper.
This is only the 5th Gum Bichromate print that I have printed and the 1st full color. This did not turn out perfect, but I am pleased enough that I am eager to do many more!

New Gum Bichromate Prints

Today I printed the third layer on two prints that I started on Wendsday. These photos represent the 3rd and 4th Gum prints that I have been able to take to completion and they have enabled me to take a couple of bigs steps forward in understanding the process. I am still experimenting and learning, but my confidence is growing.
Both of these were printed in three stages using an 8x10 lazer transparency as a negative for contanct prints. For each print I used Raw Sienna (Sun: 7 min) for the hightlights, VanDyke Brown (Partial Sun: 3.75 min) for the midtones and Lamp Black (Sun: 2.5 min) for the shadows. All pigments were mixed with Amonium Dioxide and Gum Arabic in pretty standard ratios.

Gum Bichromate Photographs

I have started to be able to spend a little more time working with the Gum Bichromates which is an alternative photo process. Photographic negatives are contact printed onto paper that I have covered with a chemical that is UV light sensitive. The solution is a mixture of Amonium dichromate, gum arabic and a water souable pigment. In a light box the print is then exposed in the sun for a specified amount of time. After exposure the print is developed in water to wash away the chemicals that were not exposed completely or only partially by the sun. After drying the print is prepared again with the same chemical, only this time a different color is added. Generally you do a print/exposure for highlight, midtones and shadow. And then the process is repeated as many times as you wish.
When starting these experiments I knew that my biggest problem was going to be obtaining a big enough negative with out having to purrchase a large format camera. But trusty PS was able to solve my problem. The photos that are shown here are ones that I had previously processed in PS and printed as standard photographic prints. I went back to these images resized them to the negative size I wanted, used curves to narrow the dynamic range for the Gum process, went to adjustments and inverted then rotated horizontally. Now I had a digital negative. I took this digital image to Office Max and for 75 cents they made a lazer transparenty which I then used for making the contact print! Neither of these prints represents the final product that I hope to eventually be able to accomplish. But here is my start.

"Rack'em Up"

These are two from this past week. I am currently experimenting with making negatives from digital images and contact printing them with the Gum Bichromate process. I do not have any good results to show yet, but as soon as I get a good print I will post it here.