G E H L I M A G I N G

Alternative Photo Processes

When a colloid mixed with a dichromate (bichromate is an outdated term) is exposed to light, the colloid becomes insoluble in water in proportion to the amount of exposure. The unexposed portions can be be washed away by immersion in water. If a pigment has been mixed in the colloid mixture, the insoluble portion will take the color of the pigment. Gum bichromate uses gum arabic and either ammonium dichromate or potassium dichromate. This is a very involved and time consuming process and a great deal of experimenting was required to find the right materials and methods to use. Prints often require more than one exposure to develop decent blacks, and those requiring only one exposure took me as much as eight hours to make. In spite of the time and effort required, this process can produce very pleasing prints. Prints made using this process are as permanent as the paper on which they're made