An envelope is a packaging product, usually made of flat, planar material such as paper or cardboard, designed to contain a flat object such as a letter. The traditional type is made from a sheet of paper cut to one of three shapes : the rhombus (also referred to as a lozenge or diamond), the short-arm cross, and the kite. These designs ensure that when the sides of the sheet are folded about a delineated central rectangular area, a rectangular-faced, usually oblong, enclosure is formed with a symmetrical arrangement of four flaps on the reverse side with overlapping edges. Jump to: navigation, search This article needs to be cleaned up to conform to a higher standard of quality. ... Look up Letter on Wiktionary, the free dictionary A letter is a written message from one party to another. ... This shape is a rhombus In geometry, a rhombus (also known as a rhomb) is a quadrilateral in which all of the sides are of equal length. ... Symmetry is a characteristic of geometrical shapes, equations and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ...

When the folding sequence is such that the last flap to be closed is on a short side it is referred to in the commercial envelope manufacturing industry as a '"pocket"'. Although in principle the flaps can be held in place by securing the topmost flap at a single point (for example with a wax seal), generally they are pasted or gummed together at the overlaps. They are most commonly used for enclosing and sending mail (letters) through a prepaid-postage postal system. A British pillar box The postal system is a system by which written documents typically enclosed in envelopes, and also small packages containing other matter, are delivered to destinations around the world. ... Look up Letter on Wiktionary, the free dictionary A letter is a written message from one party to another. ... A British pillar box The postal system is a system by which written documents typically enclosed in envelopes, and also small packages containing other matter, are delivered to destinations around the world. ...

Window envelopes have a hole cut in the front side which allows the paper within to be seen. They are generally arranged so that the sending address printed on the letter is visible, saving the sender from having to duplicate the address on the envelope itself. The window is normally covered with a transparent or translucent film to protect the letter inside. In some cases, shortages of materials or the need to economize resulted in envelopes that had no film covering the window. One innovative process, invented in Europe about 1905, involved using hot oil to saturate the area of the envelope where the address would appear. The treated area became sufficiently translucent for the address to be readable.

An aerogram is related to a lettersheet, both being designed to have writing on the inside to minimize the weight. Any handmade envelope is effectively a lettersheet because prior to the folding stage it offers the opportunity for writing a message on that area of the sheet which after folding becomes the inside of the face of the envelope. GB Christmas Aerogram (date?) An aerogram is a thin piece of foldable and gummed paper for writing a letter for transit via airmail, in which the letter and envelope are one and the same. ...

The "envelope" used to launch the Penny Post component of the British postal reforms of 1840 was a lozenge-shaped lettersheet. But if desired a separate letter could be enclosed and postage remained one penny provided the combined weight did not exceed half an ounce (about 13 grams). The Penny Post is any one of several postal systems in which normal letters could be sent for one penny. ...

A "return envelope" is a preaddressed, smaller envelope included as the contents of a larger envelope. Some envelopes are designed to be reused as the return envelope, saving the expense of including a return envelope in the contents of the original envelope. The direct mail industry makes extensive use of return envelopes as a response mechanism. Direct marketing is a form of marketing that attempts to send its messages directly to consumers, often without the use of intervening media. ...

Up until 1840 all envelopes were handmade, each being individually cut to the appropriate shape out of an individual rectangular sheet. In that year George Wilson in the U.K. patented the method of tessellating (tiling) a number of envelope patterns across and down a large sheet, thereby reducing the overall amount of waste produced per envelope when they were cut out. In 1845 Edwin Hill and Warren De La Rue obtained a patent for a steam-driven machine which not only cut out the envelope shapes but creased and folded them as well. (Mechanised gumming had yet to be devised.) The convenience of the sheets ready cut to shape popularised the use of machine-made envelopes and the economic significance of the manufactories which had produced handmade envelopes gradually diminished. 1840 is a leap year starting on Wednesday (link will take you to calendar). ... Photo submitted by Franklyncards George Wilson was a Scottish recipient of the Victoria Cross, the highest and most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces. ... ... Jump to: navigation, search 1845 was a common year starting on Wednesday (see link for calendar). ... First British Controller of Stamps, appointed by his brother Rowland Hill. ... Warren De la Rue (18 January 1815 - 19 April 1889) was a British astronomer and chemist, most famous for his pioneering work in astronomical photography. ... Jump to: navigation, search A patent is a set of exclusive rights granted by a state to a person for a fixed period of time in exchange for the regulated, public disclosure of certain details of a device, method, process or substance (known as an invention) which is new, inventive... In physical chemistry and in engineering, steam refers to vaporized water. ...

As envelopes are made of paper they are intrinsically amenable to embellishment with additional graphics and text over and above the necessary postal indicia. This is a feature which the direct mail industry has long taken advantage of, and more recently the Mail Art movement. Direct marketing is a form of marketing that attempts to send its messages directly to consumers, often without the use of intervening media. ... Mail art is art which uses the postal system as a medium. ...

Most of the over 400 billion envelopes of all sizes made worldwide are machine-made. The envelope-machine making industry is dominated internationally by Winkler and Dunnebier.

External links

Look up Envelope on Wiktionary, the free dictionary

• Making Your Own Envelopes
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