“Engraving is one of the oldest and most beautiful processes for reproducing images on paper. The appeal of engraving lies in the exquisite detail created by its three-dimensional impression. Engraving is produced when the copy is etched in reverse into a copper plate. Ink is deposited in the resulting cavity. The engraving press then forces the paper in to the cavity, creating a raised impression. The paper is literally raised with the ink adhering to the raised surface. The fact that the paper is raised is what distinguishes engraving from thermography and flat-printing.”

— From Crane’s Blue Book of Stationery, edited by Steven L. Feinberg