Method of making a magnetic flexible printing plate

An improved method of making a flexible printing plate adapted to be mounted on a magnetic cylinder of a printing press, comprising the steps of mixing a ferrous metal powder within a liquid vinyl material to form a mixture, forming a face layer of at least partially cured vinyl material substantially free of the ferrous metal powder, casting the mixture onto the face layer of at least partially cured vinyl material to form a base layer of gnerally uniform thickness, heating the base layer with the face layer to fuse the layers into a multi-layer mold sheet of substantially uniform thickness, placing the face layer of the mold sheet into contact with a porous printing plate mold having a substantially uniform thickness and a recessed impression, heating the assembly of the mold sheet and the printing plate mold, placing the heated assembly into a press having a fluid actuated diaphragm, pressurizing the diaphragm with uniform fluid pressure for pressing the face layer of the mold sheet into the recessed impression to form a printing plate having a rasied printing surface corresponding to the impression, allowing the assembly to cool while the mold sheet is being pressed against the printing plate mold, reforming the base layer including the ferrous metal powder to provide the printing plate with a precisely uniform caliper, and stripping the printing plate from the printing plate mold.