To make a color lithograph, each individual color in the design must be separated and drawn onto an individual lithographic stone. Then, the stones are printed one after another onto a single sheet, with careful registration.
The Graphic Arts Collection recently acquired a progressive series of proofs for the well-known lithograph The Darts Champion by Barnett Freedman (1901-1958). This large (590 x 920 mm) print was commissioned by Guinness for its first lithograph series in 1956 to celebrate the publication of Guinness World Records. It was printed at the Curvwen Studio and the proofs kept by Freedman for many years. Emma Mason also used it to illustrate “Who? When? Where? The Story of the Guinness Lithographs” (see: https://www.emmamason.co.uk/a/guinness-lithographs) Here’s the series: