Aquatint is a method of etching (biting lines into the surface of a printing plate) so as to create the appearance of tone, rather than lines, when the plate is printed. The key to the technique lies in the application of particles of finely powdered acid-resistant materials to the printing surface of a metal plate. When acid is applied to the plate, it eats into those areas of the metal unprotected by the particles. Pits are created in the metal that gives a grainy texture to the image or design that results from inking the plate and printing it on paper.