The Bureau of Engraving and Printing and is where U.S. money is made. The engraver's medium is metal and his paintbrush is a hard metal engraving tool. Usually working from a drawing, a painting or a photograph, engravers cut in dots, dashes, and curved lines into the master die.

You may be asking, "Why can't this process be computerized?" An engraved image is far more difficult to replicate than a computer-designed image. The combination of coarse and fine engraved lines make reproduction next to impossible.

U.S. Gov. Security Printer

A siderographer, transfers the completed, hardened engraving into a soft transfer roll. When hardened, this roll will be used to duplicate the original engraving over and over. All U.S. currency is produced using the intaglio method.
 
Plate Making The master die put under pressure, heated and an impression of the die is taken. An alto and/or relief (a raised image of the die) is cast in plastic. Multiple plastic images of the various components are made, and fitted into the necessary plate configuration consisting of thirty-two notes.Plastic altos are used to produce a series of plates, which are then carefully inspected by an engraver. Then the final chromium coated basso (recessed image) plate is made and another multiple subject intaglio plate is ready to place on the printing press.

Printing The Bureau prints currency on high-speed, sheet-fed rotary presses, which are capable of printing over 8,000 sheets per hour. The surface of the note feels slightly raised, while the reverse side feels slightly indented.

Examining Each stack is examined for defects. If the sheet meets standards, it is then ready for numbering and processing.

Overprinting A letterpress overprints with black ink the Federal Reserve District seal and its corresponding number designation. It then overprints the Treasury seal and serial numbers in green ink. Two cutters slice the notes into two note units and finally into single stacks of one-hundred notes. The units of 100 notes are banded and packaged into "bricks" containing 40 units; each "brick" contains 4,000 notes.

Portraits and Designs on U.S. Currency The design of paper currency, as well as the material used in its production, is determined by the Secretary of the Treasury.

Currency paper is composed of 25% linen and 75% cotton. Red and blue synthetic fibers of various lengths are distributed evenly throughout the paper. Prior to World War I the fibers were made of silk.