Comments
The four types of printing are: 1.) letterpress or relief printing (may include flexographic printing); 2.) intalagio or gravure printing; 3.) lithography printing; and 4.) silk-screen printing. See "Silk-Screen Printing" in Processes and "Intalagio printing" and "Lithography printing" in Activities. The image or print area is raised in the first method and recessed in the second. Rubber or rubber-like plates are used in flexography printing. In lithography, plates are made of dissimilar materials that either repell or attract the ink. An intermediate step or blanket may be used in lithographic printing, and the transfer process is called offset printing. [ILO Encyclo, "Printing and Publication"] See "Implementing Safer Alternatives to Lithographic Cleanup Solvents to Protect the Health of Workers and the Environment." [PMID 19142792]