A stamp must be affixed to a letter in order to serve its intended purpose. To accomplish this, the vast majority of stamps are gummed. Some stamps, like the ones the Dutch sent to their Asian and West Indian colonies, were sold and sent without gum. In the nineteenth century, a long boat trip to a hot climate in a humid hull meant that gummed stamps would arrive stuck together and had to be soaked in water to separate them, thereby losing their gum anyway. Sometimes the stamps were gummed upon arrival in the colony; though in India, the first issue was never gummed. The Danish West Indies (the American Virgin Islands after they were sold to the United States) issued the same stamp two ways over the years; either gummed in Denmark or gummed locally.

The gum on most early stamps posed a problem for early stamp producers. In the United States, newspaper editorials routinely complained that the stamps would not stick when moistened and that the taste of the gum was objectionable. The government was in a bind. To make the gum stickier would have meant having to apply it more thickly, which besides raising production costs would have caused the sheets of stamps to curl even more than they were already prone to do. Gum was applied wet to the printed sheets of stamps and, as it dried, it contracted, forcing the sheets into tight little rolls. Modern gumming avoids this by “breaking” the gum as it is placed on the stamp. Breaking occurs immediately after gumming, with the paper being pulled in the opposite direction from the curl, setting up small ridges or lines that, ideally, keep the stamps from curling. This method dates from early in the twentieth century. The stamps that the newspaper publishers complained about were kept from curling by hanging them to dry in sheets with weights attached at the bottom— a method that prevented curling only as long as the weights were on.

Gum is a major problem for stamp collectors, too. Many old stamps— such as the first issues of Denmark— have gum that just doesn’t want to come off. It has cracked and solidified over the years until i

936 Ostropa souvenir sheet (a specially prepared issue for philat has a consistency similar to plaster. Some gums contain sulfur, like the gum used on Germany’s 1936 Ostropa souvenir sheet (a specially prepared issue for philatelists that had postal validity as well), which reacts with water vapor in the air to produce minute amounts of sulfuric acid. The acid is too weak to harm a collector’s hands, but sheets that have not had the gum removed have now mostly disintegrated. Until about 1890, gum was of such poor quality that collectors routinely washed it off. In the last eighty years, however, collectors have reversed their previous aversion to gum with such vigor that it seems almost as if they are atoning for earlier sins. Pendulums swing; although we will be talking a lot more about gum, it would be wise to remember that gum is just one attribute of a stamp in mint condition

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