What is "viscosity printing"

n. In printmaking, an intaglio method whereby multiple colors of ink may be printed simultaneously from the same plate, utilizing inks of varying viscosity, plates with multiple levels of etching and hard and soft brayers for applying the inks to the plate.

Viscosity printing is a multi-color printmaking technique that incorporates principles of relief printing and intaglio printing. It was pioneered by Stanley William Hayter.

The process uses the principle of viscosity to print multiple colors of ink from a single plate, rather than relying upon multiple plates for color separation. It is a fine art printmaking technique, making original prints in limited editions, as it is slow and allows too much variation between proofs to make large editions feasible. Color viscosity printing is among the latest developments in intaglio printmaking. Stanley William Hayter developed it during the late 1960s in Paris.