Patent model for bank note printing: method of making plates of requisite hardness

Sellers, Alfred · ca 1864

This patent model demonstrates an invention for bank note printing which was granted patent number 41724. In the steel transfer process used for intaglio security printing, it was difficult to make a plate that was both soft enough to receive an impression and hard enough to resist distortion in the transfer process. By this invention, a hard steel plate was faced with a sheet of soft iron.