Gumming of stamps
Gum is a substance that is applied to the back of stamps so that they can be glued to a letter by moistening them.
Manufacturing
The main components of rubber coating today are mainly plastics . In most cases it is polyvinyl alcohol (PVA), a synthetic carbon- based polymer . Initially, mainly animal glue was used, a little later also vegetable substances such as dextrin or gum arabic .
For technical reasons, gumming is now generally applied before the stamps are printed . The gumming is done by machine. In the early days of postage stamps, these were often only gummed after printing. This gumming was done by hand with a brush if there were no machines .
conservation
In philately, the preservation of the gum is a decisive price criterion for unused, gummed out stamps. Philatelists differentiate between three quality levels:
- Mint never hinged - **: The gum on the stamp is in the same condition as it was delivered by the post office. This means that the rubber coating is perfect.
- Unused, folded - *: The gum on the stamp is only partially in its original condition. There is often a fold or leftover folds on the back . This form of conservation is less popular. This means that folded stamps are considerably cheaper than post-fresh ones. However, this also means that fraudulent attempts are made to smear the gum or to restore it in some other way in order to give the impression of a mint stamp.
- Ungummed, without gum - (*): The gum on the stamp is completely missing. Only very rare stamps are still collected in this form of preservation. Ungummed copies of such stamps are therefore often given the wrong rubber coating in order to increase the value. One speaks of re-gumming (in contrast to the original gumming) or new gumming.
- Some stamps, for example in times of need or in damp climates, were issued without gumming. A better preservation than (*) is therefore not possible with them.
In most postage stamp catalogs , unused postage stamps are rated according to this scheme and labeled with the internationally common symbols (asterisks) as above. Additional gumming can often be recognized by the fact that the subsequently applied gum differs in texture from the original, has flowed around the edges of the postage stamps and, in particular, has hardened the torn tooth tips. Such manipulations reduce the collector's value of the brands.
Special forms
The philatelist is not only concerned with the preservation of the gum, but also with its appearance and structure. For example, there are differences in color, some rubber coatings are shiny, others are striped or grainy. Special forms of rubber coating are:
The postal administrations often experimented with the composition of the gumming so that over time numerous different types of gumming were developed. In 1955 and 1956, for example, the Deutsche Bundespost tested gumming with a peppermint flavor . This peppermint gum, unlike normal gumming, should leave a pleasant taste on the tongue when licking the stamp. However, these attempts were discontinued after a year and have not been taken up until today.
In tropical areas , the gumming of the stamps issued was often completely dispensed with due to the high humidity . Otherwise the stamps would stick together too easily. So you had to keep glue in stock. Instead, self-adhesive postage stamps are increasingly being used, which are peeled off the carrier paper in a similar way to stickers (e.g. in Brazil). Countries in moderate climates are now also making use of it. While some issues are provided with a water-soluble intermediate layer between the branded paper and the adhesive layer with a view to collectors who want to remove used stamps from envelopes or cards, other stamps are issued without such a layer in order to make it more difficult to detach and reuse stamps that are unstamped inadvertently.
Harmful gumming
In special cases, gumming can damage or destroy a stamp. The German Reich expended example stamps with a rubber coating, the sulfuric acid content has not been neutralized and the increasingly damaged the stamp after a few years ( Ostropablock ). For these brands, it was recommended after a short time to remove the rubber coating immediately. In the case of older stamps that have been gummed with animal glue, breaks in the latter ("rubber cracks" due to fluctuations in humidity and temperature) can lead to a break through the entire stamp. Here, peeling off the rubber can prevent the stamp from falling apart at such a point.
proof
- ↑ Hänel: re-gumming . Gert Murmann.
- ↑ Hänel: What is a repaired or damaged stamp worth? . Gert Murmann.
- ^ German Empire . In: Michel stamp catalog Europe / Overseas . Publishing house of the Schwaneberger Album, 1936.
- ↑ Kreuzer / Centesimi 1850/54 . Philaforum. The stamp forum. March 21, 2008.