Formulary's Gum Bichromate Kits are some of the most versatile and least complicated of the non-silver processes.
Gum printing is unique among all the printing processes; it is distinguished by unlimited flexibility. The user has complete control and may produce prints of any color or contrast. These prints are characterized by a long, open scale that is soft and romantic, but fine detail is not possible.
Gum Printing uses water color pigments rather than metal to form the base. The paper is coated with the gum Arabic and dichromate salt. When dried paper is contact printed, the exposed areas become water insoluble. A warm water development dissolves the gum from the unexposed areas. The pigment in the retained areas forms the image. Multiple printing with different colors is a common technique.