Steve - yes, you need a UV source of light.

Jim - I see this as being more closely related to salt printing rather than to gum bichromate printing. In both salt printing and gum-silver, the image is formed by the interaction of the light on silver chloride (salt printing) or silver nitrate(gum-silver). In gum bichromate, the light interacts with the gum, hardening it in direct proportion to the amount of light falling on it, which is related to the different densities in the negative. The pigment dissolved in the gum provides the image, but it is the gum that reacts to the light.