Although the word “etching” is commonly used to describe any print produced using intaglio printing methods, there are actually several types of etching techniques, each of which produces a different effect. Over the centuries, artists from Rembrandt to Picasso have employed various etching techniques to completely different ends.

Traditional etchings, which resemble pen-and-ink drawings and date to the 16th century, are produced by coating a sheet of copper with a wax mixture known as a ground. After the artist scraps away the ground with an etching needle, the sheet is placed in an acid bath. The acid cuts into, or bites, the exposed areas, leaving the copper below the ground untouched. The ground is then removed from the plate while is then exposed to ink, filling the crevices created by the acid. Finally, when the plate is pressed against a sheet of paper, the ink is transferred.

Soft-ground etchings are a more recent technique, dating to the mid-to-late 1700s. As with an etching, a plate and ground is employed, but the wax used in soft-ground etchings is..., well, softer, allowing it to be lifted from the plate by pressure from a textured surface or the marks of a writing instrument over a sheet of paper that has been laid upon the ground. The resulting bite of the subsequent acid bath is thus more uneven, suggesting the irregular markings of a crayon.