Color guides are one-of-a-kind pieces of hand-colored comic art, part of the production process of a comic book (except for artists hand painting their pages with no intermediate pencils and inks). They should not be confused with color proofs or color separations which are often simply stats or copies of the art done at the printer for testing. See also Color bluelines which is a slightly improved version. For most of the 20th century, colorists worked on photostats or photocopies of the inked original art using brushes and dyes which were then used as guides to produce the printing plates. Now, this work is usually done using digital media, with printing separations produced electronically. Color guides are usually the same size as the published comic book and contain additional notes to the printer's color separation department indicating which color tones to use for the proofs (thus the name "color guide"). They are usually far less expensive than all other original artworks in the production process. Search for color guide* on ComicArtTracker. Detail of original color guide for Dave Gibbons Watchmen #1 Page 1 In Europe, artists used to tape a sheet of tracing paper on top of their pages with color indications, usually with colored pencils (see indication* couleur*). Surplouf by Jean Cézard - original art without and with its color guide on tracing paper Sometimes also, but more rarely, artists directly painted color indications on the back of the original art: colors could be seen by transparency when held up to light. Sergio Toppi - original art (front) / colored back / held up to light See: A Brief and Broad History of Post Golden Age-Pre-Digital Comic Book Coloring - 1990s Era Color Guide by Walt Simonson