ABSTRACT
This chapter explores best practice in registering, coating, exposing, and developing and then monochrome, duotone, tricolor and quadcolor gum printing. Even monochrome gum is a multi-layered printing process. Preshrinking the paper is the first step to ensuring good registration. Use a very light flicking motion to smooth out any brush strokes or marks and the coating is done. Best practice is to expose a coated layer immediately upon dry, especially in humid climates. There is a thing called "dark reaction" which is non-image hardening of the colloid even without light exposure of any sort which results in a low contrast, fogged print. Develop the gum print right after exposure or continuing action can be a problem, like dark reaction, where the dichromate continues hardening the layer in a non-image exposure way. Developing a gum print can be done in two ways: automatic development and mechanical development. Monochrome gum today does not usually mean mono-layer gum but mono-color gum.
