In order to determine whether a stamp has been regummed, a knowledge of stamp printing is required. When stamps are printed, they are printed on a sheet of paper that is then gummed and perforated. The order in which this is done is the clue to detecting the type of gum: on genuinely gummed stamps, the perforations are applied after the stamp has been gummed. On regummed stamps, the gum is applied after the perforations have been made. If you take an ordinary fifteen-cent commemorative and break it from the sheet, you will notice the way the perforations slightly fray and how the gum does to extend around the perforation tips. On regummed stamps, the gum tends to glob on the perforation tips, extending slightly beyond them and making the perforation tips brittle to the touch.
This is the major test. But now, we are told, regummers are using high-technology sprayers to duplicate closely the applied characteristics of genuine gum. More times than not, they wash the original “hinged” gum off the stamp, and then reapply it, with no “hinged” characteristics. The gum looks original, and is, but it has been tampered with and such a stamp is not as popular with serious philatelists and is sold at a lower price. The best advice is to buy never hinged (NH) stamps that date back to about 1920, which is the period when the gum fad began and when reasonable stacks of philatelic material were available from which true NH material could surface. But, before 1920 (and this is increasingly true for each decade that you go back, a hinge mark is your surest guarantee that you are indeed buying original gum.
But what does “never hinged” really mean, anyway? It doesn’t only mean, as some literal graders would define it, “never having had a hinge.” An NH stamp must, of course, be never hinged, Post Office Fresh. The stamp must never have been touched with a hinge and the gum must be, in all ways, pristine. A technical description such as: “Small gum soak, and large sticky pieces of black gummed paper stuck to back, otherwise NH,” means no more than, “Very Fine but for a small hole,” or “Super but for a large disfiguring tear.” A stamp is either NH or it is not NH; there is no “NH but!”
Gum is a vital determinant of stamp value—and probably from today it will always be so. But, consider this, early no gum stamps are beginning to rise in price as fast as the original gum (og) ones are. A perfect original gum set of Columbians would sell for about $20,000; never hinged for about $50,000; and no gum for about $12,000. it might be going too much out on a lib to predict the renaissance of no gum stamps; but certainly this prediction is no more outrageous than the prediction twenty-five years ago of the immense rise of “og, NH.”
Be cautious in your condemnation of regummed stamps, though. The advent of the modern sealed stamp mounts has put a severe strain on gum. Gum, especially in hot and humid climates, tends to sweat or run slightly, which can make a stamp look like it has been regummed. This is a natural process, but one that is hastened when a stamp is in a mount. The mount acts as a miniature sweat-box, so if you have your stamps in mounts, be sure there is adequate ventilation and that the stamps are kept in a cool place all year round.