Gum (Adhesive) – Wikipedia

In philately, the and is a substance applied to the back of a stamp to allow it to adhere to a letter or other postal support. This generic term applies both for traditional gums such as arabic gum and modern synthetic gums. The state of conservation of the gum is an important parameter when estimating a stamp ^{[ first ]} .

Before the postage stamps exist, it was the recipients who had to pay to receive the letters sent to them. The postal rates were based on the distance traveled by the letter as well as by its weight. It was Sir Rowland Hill who brought the solution to this exceeded system thanks to the early payment and the appearance of the postage stamp ^{[ N 1 ]} . The first postal stamp in history is the Penny Black issued by the United Kingdom of Great Britain and Ireland in 1840 ^{[ 2 ] , [ 3 ]} . This known stamp was erased, but many stamps of XIX ^{It is} century were nevertheless issued without gum and this sometimes for lack of means (for example, the first Uganda Cowries program produced in 1895 with a typewriter). The extreme tropical climatic conditions (sun and humidity) were also a problem for the conservation of the gum of the stamps of the countries concerned (Belgian Congo, Suriname …) ^{[ first ]} . Finally, some stamps intended to be sold exclusively for collectors have been delivered without gum, such as the Farley’s Follies US Souvenir Leaves (in) from 1933. The gum of the first stamps of Great Britain was called cement ^{[ 4 ]} and was prepared from a mixture of potato starch, wheat starch and gum arabic ^{[ 5 ]} .

Initially, the eraser application was made after printing but before perforation, often due to the fact that the paper had to be wet to be able to be printed properly. There are many historical examples where stamps were erased after being perforated, but it remains unusual. Nowadays, stamps are printed dry on pre-glomed paper ^{[ 6 ]} .

On the first stamps, the gum was applied manually, using a brush or a roller. It was not until 1880 that the street printer invented a machine that automatically erases the back of the stamp leaves. Since then, gum has always been applied evenly using a machine.

The most critical problem due to the scrub operation is its tendency to bend ^{[ 7 ]} The stamp due to reactions between gum and paper which are not at identical humidity. In extreme cases, the stamp can wrap on itself and form a fine tube of paper. Many devices have been put in place to try to limit this phenomenon, but the problem still persists. On Swiss stamps of the 1930s, the printing Courvoisier used a machine to break the gum by passing a roller with small points on the gum that has been wearing from the particular name of broken eraser ^{[ 8 ]} Because of its embossed appearance. Another technique used was to decide the gum thanks to a knife after its application. In some cases, the problem is solved by itself that the eraser cracks while drying.

The aspect of the eraser ^{[ 9 ]} On stamps varies depending on the type of gum used and according to the application method, its shade of going from colorless to dark brown. Here are some types of gums ^{[ 6 ]} Frequently used on stamps (the list is not exhaustive because of very specific gums have been produced locally and temporarily ^{[ N 2 ]} ):

• Gum Arabic: gum the most widely used until the 1960s. New, it has a shiny appearance and easily glue to the fingers. It is a gum very subject to humidity and the appearance of rust ^{[ ten ]} . She quickly adheres to paper, but is so easily removed. It frequently happens that new stamps of stamps are glued to each other because of this sticky eraser ^{[ 11 ]} .

• Synthetic gum: gum produced from polyninyl alcohol and whose white color is brought by the dextrin extracted from starch. It is often abbreviated by letters APV ^{[ first ]} . It is resistant to humidity and does not stick to the fingers. It takes more time to stick, but adheres more strongly ^{[ 11 ]} .

• Tropical eraser: gum which reacts less strongly to strong humidity and heat. It has a more or less dark brown appearance ^{[ 11 ]} .

Some stamps have received an eraser with a particular pattern resembling a watermark, probably to ensure additional security against the counterfeiters. German stamps of 1921 have an eradication with wave patterns while Czech stamps have had the initials of the country CSP ^{[ 5 ]} in their gum from 1923 ^{[ twelfth ]} .

Because of the lack of resources and the dramatic situation according to the Second World War in Germany, savings were made on the quantity of erases applied to stamps. This eraser called economics (in German: spargummi ) was not thus affixed on the entire surface of the stamps ^{[ 13 ]} .

From the 1990s, the use of self -adhesive stamps or self -adhesive stamps was largely intensified especially for the series of current use. The material used is an adhesive that does not require humidity, solvent or heat to be activated. Therefore, the support of this new type of stamp is an icy paper that allows them not to stick as strongly as on paper ^{[ 14 ]} . It is a country with a tropical climate, the Sierra Leone which made the first use of a sticker stamp in 1964 ^{[ 4 ]} . The United States waited 1974 ^{[ 15 ]} To issue their first sticker Christmas stamp, but it has not been very successful. Canada is followed by Japan and the United States at the end of the 80s in the greater employment of sticker stamps ^{[ 16 ]} . In France, the Marianne du Bicentenaire inaugurates this type of stamp in 1990.

The use of self -adhesive has made it possible to avoid concerns of hygiene since it is not necessary to humidify the stamps to be able to stick them. Ease in their use and in their manufacture (particular forms ^{[ N 3 ]} ) has also been brought. Nevertheless, due to the difficulty in taking them off from their postal support, the sticker stamps are not appreciated by philatelists ^{[ ten ]} .

In 1965, an English study on the transmission of viruses and bacteria on erased paper brought: Although no bacteria or pathogenic virus has been isolated on envelopes samples obtained from various sources, the gums used in the manufacture of stamps have shown a protective effect against death due to desiccation for bacteria and virus introduced into them. Bacteria could also be demonstrated in these gums. The authors add as a warning: The stamps are very often treated with negligence when presented on the counter of a post office, while the buyer licks them without hesitation. The present work shows how easily the bacteria can adhere to the surface of the soft paper which has been slightly moistened; And the finger is an important source of humidity and bacterial contamination. ^{[ 17 ]}

In 1996, an episode of the Popular Sitcom Seinfeld presented a character (Susan Ross) who was poisoned after licking the flap with too many erased envelopes. This episode was anecdotally linked to an increase in concerns about health risks to lick gummed paper and it has been speculated that it would have contributed to the growing popularity of sticker stamps, at least in the United States.

Many traces of hinges are visible at the back of this stamp.

Different states of conservation [ modifier | Modifier and code ]

The chopping of stamps is an important parameter for collectors, although its presence is rarely used to differentiate a common stamp from a rare stamp. Nevertheless, his condition is reflected in the evaluation of new stamps. Several quality levels are distinguished by philatelists ^{[ 18 ]} :

• Timbre New without a hinge ** : this state is known under its English abbreviation Mnh ( Mint Never Hinged ). The stamps must be in the same state as leaving the post office, that is to say with an intact eraser and without hinge or hinge traces. This is the most sought -after conservation state that brings the highest odds ^{[ N 4 ]} .

• Timbre new with hinge * : this state is known under its English abbreviation MH ( Mint Hinged ). A hinge or traces of hinges are present at the back of the stamp and even if there is a part of the original gum, the stamp is no longer considered completely new. The dimensions for these stamps decrease sharply and they are therefore less sought after.

• Timbre New without gum (*) : this state is known under its English abbreviation Mng ( Like no rubber ). The stamps have a new appearance but the eraser is not present. These can be stamps that have never been erased or stamps whose gum has been intentionally removed. Their rating is generally identical to new with a hinge.

• Obliterated : stamps have received an obliteration and do not have a de facto gum.

Some stamps have been emitted without gum ^{[ 19 ]} , either because of a lack of means, or to prevent the stamp leaves from sticking together in tropical countries. These stamps are therefore only found in quality (*).
In addition, before the Second World War, the strip stamp albums did not exist and the collectors therefore stuck their new stamps as well as obscured on paper albums using hinges. It therefore appears that the number of ancient stamps ( XIX ^{It is} century) are quite rare in quality **, especially for good odds. The consequence is that many old stamps were subsequently reached in order to make them win ^{[ 20 ] , [ 21 ]} . The detection of these false stamps must therefore be an important part of philatelic expertise. In any case, will the stamps beyond only the new stamps without gum ^{[ 15 ]} .

Varieties [ modifier | Modifier and code ]

The text printed at the rear indicates that this Russian stamp of 1917 has a course equal to that of a money or copper currency.

Stamps containing text, figures or symbols printed on the eraser have a particular interest in thematic collectors ^{[ 13 ]} .

There are also stamps printed by mistake on the erased side. These are strongly sought by collectors interested in unusual varieties.

As explained previously, the gum could frequently lead to the winding of new stamps on themselves. To avoid this, certain postal authorities, such as Germany in the 1930s and 1940s, decided to break the gum using rollers bristling with points, which causes its embossing. The orientation of this grid is thus used to distinguish the different series from a type of stamp ^{[ 22 ]} .

Damage due to gum [ modifier | Modifier and code ]

The OSTROPA commemorative block has its paper discolored by the acid present in the chips of stamps. The paper also deteriorates in the watermark.

Precautions must be taken during the operation which applies gum on stamps, in particular if it is prepared from natural elements. The acid contained in the gums can in fact destroy the paper from the stamp ^{[ 15 ]} . There are notable cases such as the OSTROPA commemorative block (of) issued in Germany in 1935 and German-style Zeppelin type posts in 1936 ^{[ 23 ]} .

Thick gum on certain older stamps, in particular those of Austria-Hungary, tends to break due to changes in humidity and air temperature. Such variations can also affect stamp paper and cause deterioration.

In such cases, stamp catalogs recommend removing gum to avoid damaging stamps further ^{[ 15 ]} .

Notes [ modifier | Modifier and code ]

References [ modifier | Modifier and code ]