Scratchboard is considered a form of direct engraving in which the artist, using a variety of sharp tools, scratches through a top black ink coated surface revealing a white clay under layer, usually on a board or cardboard. As the initial drawing surface is completely black, the artwork image is essentially created though "subtractive” drawing. Though traditionally a black and white medium, color can then be added if desired using inks, colored pencils or paints.