A plate number is a number printed in the margin of a sheet or roll of

postage stamp A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the fa ...

s, or on the stamp itself, which shows the

printing plate Printing is a process for mass reproducing text and images using a master form or template. The earliest non-paper products involving printing include cylinder seals and objects such as the Cyrus Cylinder and the Cylinders of Nabonidus. The ea ...

used to print the stamps.

A plate number is the serial number of a printing plate. It is printed in the selvage or border of a pane of postage stamps.

Philatelists Philately (; ) is the study of postage stamps and postal history. It also refers to the collection and appreciation of stamps and other philatelic products. Philately involves more than just stamp collecting or the study of postage; it is possi ...

and

stamp collectors Stamp collecting is the collecting of postage stamps and related objects. It is an area of philately, which is the study (or combined study and collection) of stamps. It has been one of the world's most popular hobbies since the late nineteenth ...

analyze or collect plate numbers and stamps with different plate numbers, often as a

block Block or blocked may refer to: Arts, entertainment and media Broadcasting * Block programming, the result of a programming strategy in broadcasting * W242BX, a radio station licensed to Greenville, South Carolina, United States known as ''96.3 ...

, thereby known as a

plate block A plate block is a block of stamps from the edge of the sheet which shows the ''plate'' or ''cylinder'' from which the stamps were printed. Background The numbering of printing plates has long been a part of quality control in the printing proc ...

. The American Plate Number Single Society (APNSS) is an example of a specialist philatelic society which focuses on single stamps with plate numbers. APNSS is affiliate #178 of the

American Philatelic Society The American Philatelic Society (APS) is the largest nonprofit stamp collecting foundation of philately in the world. Both the membership and interests of the society are worldwide. History The organization, originally named the ''American Phil ...

A plate number coil (PNC) is a

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

with the number of the

or plates printed on it. The plate number typically appears as one or more small digits in the margin at the bottom of the stamp. The plate number may be centered or, on some coil issues, located toward the right. Although most plate numbers are composed of just numbers, both a combination of letter and number may be used. In the case when a letter is represented in the plate number, an upper case letter usually appears at the beginning or at the end of the sequence with the former serving as a good identifier of the stamp printer. The plate number is on one stamp out of the number of stamps printed by a single revolution of

rotary printing press A rotary printing press is a printing press in which the images to be printed are curved around a cylinder. Printing can be done on various substrates, including paper, cardboard, and plastic. Substrates can be sheet feed or unwound on a continuo ...

used to print the stamps. In the example above, which is a closeup of a strip of 1996 "flag over porch" self-adhesive stamps, we can see a plate number comprising five digits, one for each color layer. The digits are quite small, and often hard to read because they are blurred by the

halftone screen Halftone is the reprographic technique that simulates continuous-tone imagery through the use of dots, varying either in size or in spacing, thus generating a gradient-like effect.Campbell, Alastair. The Designer's Lexicon. ©2000 Chronicle, S ...

. Also, in this example, the numbers on the left, known as micro-printing, usually denote the year the issue is copyrighted or printed and, therefore, should not be mistaken as the plate number. While there are other factors such as condition and centering, the philatelic value of a PNC single or strip highly depends on its plate numbers with some plate numbers commanding higher catalog values due to their rarity and strong collector interest. Collectors specializing in PNC collecting typically save plate number coils in the following formats: # PNC5 – Plate Number Coil 5 – A strip of 5 mint stamps with the plate number coil on the center stamp. # PNC3 – Plate Number Coil 3 – A strip of 3 mint stamps with the plate number coil on the center stamp. Although many collectors still collect coils in this format, a larger number of these collectors prefers the PNC5 format. As a result, a PNC3 is less desirable than a PNC5 as evidenced by many specialized stamp catalogs now assigning much higher premiums to PNC5 formats of earlier coil issues. Initially, saving PNC3s had been the practice adopted by many collectors and dealers alike and, therefore, not many early issues were saved in the longer format. # PNS – Plate Number Single – A single unused or used plate number coil stamp. If used, the plate number must be identifiable and not be obliterated by the postmark, although many precanceled issues, in order to show their proper use and to be collectible, should not receive any postmarks. # On cover – An envelope bearing a used plate number coil stamp with a contemporary

postmark A postmark is a postal marking made on an envelope, parcel, postcard or the like, indicating the place, date and time that the item was delivered into the care of a postal service, or sometimes indicating where and when received or in transit. ...

tying the stamp to the envelope. Many collectors prefer the cover to have the correct postage and proper stamp or stamps used for the envelope. An example of an improper use is to combine many precanceled stamps and older issues on an envelope as payment for a first class postage. Although this practice is allowed by the Post Office, most collectors find this and stamp collector contrived or

philatelic cover A philatelic cover is an envelope prepared with a stamp(s) and address and sent through the mail delivery system for the purpose of creating a collectible item. Stamp collectors began to send mail to each other and to themselves early on, and p ...

s less desirable. Some coil issues will require collectors to save longer than even the PNC5 mentioned earlier. For example, the United States Crops coil stamps, issued in 2006, have five designs with only one of the stamp designs bearing a plate number. While some collectors will save this issue as a PNC5 and no shorter, others may choose to save it as a PNC11 so that the stamps of the same design with and without the plate number are represented.

Notes

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External links and further reading

Glossary of stamp collecting terms specific to plate number single collecting
Philatelic terminology