Gum printing uses a solution of watercolor paint, gum arabic, and a sensitizer. This solution is coated onto a substrate (watercolor paper, in my case), then exposed to light using a contact printing method. In most of these prints, up to three layers are used, as the color is rather transparent. The images themselves are enlarged from 35mm film, then printed digitally as negatives to use for the print, so the process is analog to digital to analog. The prints are rather unique in that the process is pretty intuitive as for the mixing of the gum solution.