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Scratchboard or scraperboard refers to both a medium, and an illustrative technique using sharp knives and tools for etching into a thin layer of white China clay that is coated with black India ink. Scratchboard can also be made with several layers of multi-colored clay, so the pressure exerted on the instrument used determines the color that is revealed. There is also foil paper covered with black ink that, when scratched, exposes the shiny surface beneath. Scratchboard can be used to yield highly detailed, precise and evenly textured artwork.
Modern scratchboard originated in the 19th century in Britain and France. As printing methods developed, scratchboard became a popular medium for reproduction because it replaced wood, metal and linoleum engraving. It allowed for a fine line appearance that could be photographically reduced for reproduction without losing quality. It was most effective and expeditious for use in single-color book and newspaper printing. From the 1930s to 1950s, it was one of the preferred techniques for medical, scientific and product illustration. During that time period, Virgil Finlay made very detailed illustrations, often combining scratchboard methods with traditional pen & ink techniques, and producing highly detailed artworks. In more recent years, it has made a comeback as an appealing medium for editorial illustrators of magazines, ads, graphic novels, and one of a kind pieces of fine art displayed in galleries and museums internationally.
The technique 
Depending on the intent of the artist, several areas may be cleared out for layering with watercolors, airbrush, ink, color pencil or acrylics. These layers are then scratched off one by one to create different shades of color that blend into and highlight certain parts of the image. It can then be retouched with more paint as necessary. This technique can yield an image that appears remarkably lifelike. Contemporary illustrators sometimes prefer to add color afterwards in Adobe Photoshop, Corel Painter, CorelDRAW, or Adobe Illustrator.
Using a sharp, angled blade or scratch tool an outline is made on the surface of the scratchboard. Scratchboard can be purchased in either all black or all white sheets. Shadows and highlights are created by "scratching" away at the board. Artists using the black scratchboard may add transparent color mediums after scratching and then go back and scratch more. This can be done several times, creating depth. Artists using the white scratchboard paint or draw black or color areas onto it and then proceed to scratch into the black portions to create their drawing. Alternatively, the cleared portions of the scratchboard may be left blank for a stark black-and-white image. Various techniques such as hatching or stippling can be used to texture and detail the image further. The 14" X 18" scratchboard Sunflower And Silver by Diana Lee is an example of black scratchboard colored with transparent ink. An extreme close up lets the detail of the scratching be more easily seen.
Materials needed 
Scratchboard itself comes either with a paper (cardboard) backing, or a hardboard. While the cardboard does have its uses, as it can be easily cut into size, the hardboard is much superior, giving greater stability to the work, being able to be corrected more often, and being able to be framed without glass.
Several tools have been created specifically for scratchboard; however any sharp implement will do though a range of blades of different thicknesses allows the removal of more or less of the ink at will. Interesting textures can be created by using tattoo needles, electric erasers and hard point scribes. Isopropyl Alcohol on a cotton swab or cotton ball, sandpaper and non oily, fine, steel wool are also useful for removing large areas, and creating texture.
Coloring scratchboard, black or white boards, can be done with many mediums applied with paint brush, air brush, and even cotton balls.
See also 
- Merritt Dana Cutler, Scratchboard Drawing, 1949, Watson-Guptill Publications.
- Ruth Lozner, Scratchboard for Illustration, 1990, Watson-Guptill Publications, ISBN 0-8230-4662-1
- Merritt Cutler, "how to cut drawings on scratchboard", 1960, Watson-Guptill Publications, ISBN 0-8230-2350-8
- Diana Lee, Starting From Scratch, 2012, CreateSpace Independent Publishing Platform, ISBN 1-4775-5881-0