Drypoint is an intaglio process, which means that the ink is pulled from below the surface of the plate. Traditionally copper is used as a matrix which is scratched into, each line raising a burr which traps the ink, creating the image. Any areas which have not been scratched remain smooth so any ink can be wiped off the top to give white or light areas. This is a non-caustic form of intaglio which doesn’t require acids or caustics to etch the plate.