Coloring the edges of books appears to be virtually as old as the codex itself, the earliest known example being purple edges on a 4th century book. Red, ochre, and yellow were often used in the 15th to 17th centuries, while solid red edges sprinkled with yellow were popular in the first half of the 16th century. Colored edges have been common to the present day in miscellaneous binding and from the late 19th century on edition bindings.
Although the coloring of edges appears to be purely for decorative effect, its actual function has always been to protect the edges from dust, dirt, and handling. See also: ANTIQUE EDGES ;FORE-EDGE PAINTING ;GILT EDGES ;MARBLED EDGES ;RED UNDER GOLD EDGES ;ROUGH GILT ;
Primary colors are: red, yellow, and blue. Secondary colors, derived from primary colors, are: Primary Colors Secondary Colors red and yellow orange yellow and blue green red and blue purple Tertiary colors, derived by combining primary and secondary colors, are: Primary Colors Secondary Colors Tertiary Colors red and yellow orange citrine yellow and blue green red and yellow orange russet red and blue purple yellow and blue green olive red and blue purple