Knife (envelope)
Encyclopedia
The term knife is used to describe the cutting die for envelope
or wrapper
blanks. It is called a knife rather than a die in order to reserve the term die to describe the object which makes a embossed printed impression of the stamp
or indicium on the envelope. Traditionally, a knife would normally be made of forged steel. It was placed on a stack of paper with the sharp edge against the paper. The press head forced the cutting edge all the way through the stack of paper. The cut blanks were removed from the knife and the process repeated. Not only could it cut out the odd shape of an envelope, but a knife could be used to cut out shapes of airmail stickers or gummed labels in the shape of stars or circles. The variety of shapes a knife could cut would be infinite.
In philately
, Thorp
knife numbers were, and still are, used to describe the height, width, shapes and folds of envelopes generally numbered in the order of their discovery by collectors. The United Postal Stationery Society
(UPSS) now has its own numbering system for envelope knives which is seeing more current use.
Envelope
An envelope is a common packaging item, usually made of thin flat material. It is designed to contain a flat object, such as a letter or card....
or wrapper
Wrapper (philately)
In philately a wrapper is a form of postal stationery which pays the cost of the delivery of a newspaper or a periodical. The wrapper is a sheet of paper, large enough to wrap around a folded or rolled newspaper and with an imprinted stamp to pay the cost of postage...
blanks. It is called a knife rather than a die in order to reserve the term die to describe the object which makes a embossed printed impression of the stamp
Postage stamp
A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are made from special paper, with a national designation and denomination on the face, and a gum adhesive on the reverse side...
or indicium on the envelope. Traditionally, a knife would normally be made of forged steel. It was placed on a stack of paper with the sharp edge against the paper. The press head forced the cutting edge all the way through the stack of paper. The cut blanks were removed from the knife and the process repeated. Not only could it cut out the odd shape of an envelope, but a knife could be used to cut out shapes of airmail stickers or gummed labels in the shape of stars or circles. The variety of shapes a knife could cut would be infinite.
In philately
Philately
Philately is the study of stamps and postal history and other related items. Philately involves more than just stamp collecting, which does not necessarily involve the study of stamps. It is possible to be a philatelist without owning any stamps...
, Thorp
Prescott Holden Thorp
Prescott Holden Thorp , of New Jersey, was a stamp dealer who was a recognized world famous expert on stamped envelopes of the United States.-Philatelic literature:...
knife numbers were, and still are, used to describe the height, width, shapes and folds of envelopes generally numbered in the order of their discovery by collectors. The United Postal Stationery Society
United Postal Stationery Society
The United Postal Stationery Society was formed July 1, 1945 from the merger of the Postal Card Society of America, in existence since 1891, and the International Postal Stationery Society, founded 1939. Current membership stands at about 1,000. The organization's journal since 1949 is called...
(UPSS) now has its own numbering system for envelope knives which is seeing more current use.