Morning Mist, aquatint
If you have ever wondered how the fine tonal areas are created in an etching, here is an example of a modern method.
The idea is to create a speckled pattern of an acid resistant material on the plate so the acid can eat around the speckles, leaving tiny raised metal points. When ink is applied and then wiped with rags, the depth of the etch determines how much ink remains on the plate, and therefore, how dark the printed tones. In the example at left, the palest tones resulted from a 10 second dip in the acid, while the darkest areas soaked in the acid about 15 minutes.
So what is thus mysterious speckled resist? In modern times, we can use spray enamel paint for a quick and reliable method to cover the plate in a fine and even mist.