The Smithsonian Postal Museum houses a number of interesting tools and machines which have been used to produce postage stamps. Together they embrace all the equipment which would have been found in the stamp production rooms of the Bureau of Printing and Engraving in the 1920s.
The first step in preparing a new issue using this equipment was design development. An artist transferred his work to special, treated tracing paper, which was laid on a blank die. Several methods were used to lightly outline the design using an engraving tool. Two basic techniques were used to prepare the die. In one, called 'line (or Intaglio) engraving', the printing part of the die was cut in recess into the die in reverse and from right to left. Any portion of the die surface left uncut would not hold ink, while the recessed lines would. Borders and letters were done first, usually using a rose engine lathe and a straight line ruling machine. The central subject was engraved last to protect its delicate art work. This was executed by a master engraver using a combination of acid etching and hand-cutting. The die was then hardened and the design taken up on a softened transfer roll mounted in a transfer press.