Which process involves acid biting into a copper plate?

The process that involves acid biting into a copper plate is aquatint etching. Aquatint is a form of intaglio printmaking that allows for the creation of tonal effects and textures on a metal plate. The technique typically uses powdered resin that is sprinkled onto the plate and then heated, causing it to adhere. When the plate is submerged in an acid bath, the acid bites into the exposed metal areas, creating a texture that holds ink for printing.

This method is known for its ability to produce a range of tonal variations, akin to watercolor effects. The use of acid is pivotal in aquatint because it allows for the controlled etching of the plate to achieve desired shades and gradations.

In contrast, frottage involves creating textures by rubbing a pencil or other tools over a textured surface. Relief sculpture and linocut both refer to forms of printmaking where the raised areas are inked and printed, but neither involves the use of acid or a biting process on metal plates. Understanding the characteristics and processes of these different techniques clarifies why aquatint etching is uniquely associated with acid biting in printmaking.