Step 1: Analyze the process described. The technique involves painting acid directly onto an already aquatinted plate to create free-form, painterly tonal areas.
Step 2: Identify the correct term. This technique is called Spitbite. The name originates from the traditional practice of mixing the acid with saliva ({spit}) to control its viscosity and corrosive action, allowing the artist to "paint" with it. Today, gum arabic is often used instead of saliva, but the name remains.