Sometimes referred to as scraperboard (especially in Great Britain), but usually called scratchboard in North America and Australia, is a form of direct engraving where the artist scratches off dark ink to reveal a white or coloured layer beneath. Scratchboard refers to both a fine-art medium, and an illustrative technique using sharp knives and tools for engraving into a thin layer of white China clay that is coated with dark, often black India ink. 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. Works can be left black and white, or coloured.

(https://en.wikipedia.org/wiki/Scratchboard)