47P4 90c Washington plate proof on card

Cardboard plate proofs, in all but a very few cases, were a post-production product. The U.S. Post Office Department requested that these proofs be produced on at least five separate occasions (1879, 1882, 1890, 1893 and 1894). Each time the USPOD asked the current banknote company of record to produce 500 sets of cardboard plate proofs, the department requested an example of each of the stamps issued from 1847 until the year of the request. This included all regular issues, postage due, special delivery, newspaper and periodical, departmental, Official seal and the two government carrier issues.

The banknote company would pull proofs of enough sheets of each issue to produce 500 sets of singles. The sheets were cut into singles, and each issue, such as the 1861 issue, was placed into a proof distribution envelope. The envelope style changed with each issue. It is possible to determine which printing produced a particular plate proof. The printing is determined by the thickness of the cardboard and the shade of the ink.

The plate proofs were requested by the Post Office Department so that it could fill requests for examples of our nation’s past postage stamps. These requests came not so much from collectors but from members of Congress who had been asked by a constituent for examples of old postage stamps. A complete set, housed in 17 envelopes, would be put into a number No. 10 penalty envelope along with a typed letter thanking the congressman for his inquiry, and into the mailstream it would go. Over a 16-year period, 2,500 sets were distributed in this manner.