Design and Specifications
A body known as the Citizens' Stamp Advisory Committee is responsible for choosing what stamps get made. The committee takes recommendations from all over the country for new stamp ideas and meets regularly with United States Post Office staff. Once a new stamp design has been chosen, the committee hires an artist to design it. Together, the committee and the artist or designer finalize all of the necessary specifications for the stamp: size, color, design and even the printing process to be used.
Printing
The designs and specifications for new stamps are then given to the Bureau of Engraving and Printing or outside contractors to be printed. They are usually printed using one of two methods: the intaglio process or the offset process. Intaglio is the oldest way to make stamps and it is more time-consuming than the offset process. However, intaglio is still widely used because of its ability to create stamps with more distinct images.
The Intaglio Process
In the intaglio process, the stamp image or design is engraved, scratched, or etched by hand onto a "master die." The engraved image on the die is then pressed onto what is known as a transfer roll. From the transfer roll, this relief of the image is then pressed onto a printing plate. (One well-known version of the intaglio process, called "gravure," entails first transferring the image to the plate photographically.) The printing plate with the relief of the image is then set in the press, coated with ink and pressed onto paper fed into the press in rolls. For a stamp, of course, the paper (usually "wove" paper is used in the U.S.) will already have glue on the back.
The Offset Process
The other common method for printing stamps is offset lithography, which is often used in conjunction with the intaglio process. In offset, the stamp image or design is transferred photochemically to an aluminum plate. The plate is set in the printer and coated with ink and water (ink on the image; water on the non-image portions of the plate). It is then pressed against what is known as a rubber "blanket," which is pressed against the paper being fed into the printer, producing the final image and the new stamps.
