What process is used to etch lines into a metal plate in intaglio printing?

In intaglio printing, the process used to etch lines into a metal plate is chemical etching. This technique involves applying a resist to the plate, followed by immersing the plate in an acid bath. The acid etches the exposed areas of the metal, creating grooves that hold ink. This method allows for a variety of line qualities and textures, making it a preferred choice for producing intricate and fine details in prints.

The choice of mechanical engraving or carving with a burin refers to direct engraving methods that physically cut into the metal surface rather than using a chemical process. Although these techniques are also valid methods of creating intaglio plates, the question specifically asks for the process of etching, which aligns with the principles of chemical etching. Heat transfer is unrelated to the intaglio process and does not apply to the creation of etchings in metal plates.