No matter how good a system is, someone will try to manipulate it. Though the early Postal Service was a wild success (enough that the first price change was a reduction in rates), the government became concerned about stamp reusage. While no definitive proof exists that people were reusing stamps in large numbers, it was a possibility. Many post offices had no official stamp-canceling devices and simply marked stamps with an ink pen, or with intricate “fancy cancels” carved from cork. Some of the cheaper inks used for cancelling stamps could simply be washed off.
Although several devices were patented, the Post Office decided to use a device that would imprint each stamp with a small pattern of geometrical bumps, intended to lightly damage the fibers of the stamp and make cancellation ink indelible. Initially called “embossing,” this mark is now referred to as a “grill.”
Stamp sheets would first be gummed, then the grill would be embossed on the paper, then the stamp would be printed with the design. (In fact, this knowledge can be used to detect gum that has been added to a grilled stamp in hopes of increasing its value. According to AmericanStampDealer.com, “If you have an unused grilled stamp with gum, check the points very carefully to detect if there is any residual gum. A gum spillover of this type is the simplest means of detecting a regumming job. Remember the process; gumming, embossing (or grilling) and then printing.”)
Grilling was standard for a relatively short period of time, from 1867 through 1871, though some stamps have been found grilled as late as 1875. This short period of use, combined with 11 different types of grilling, resulted in making certain grilled stamps extremely rare and valuable. The 1-cent Z-grill stamp was thought to be one of the rarest USPS stamp, with only two such stamps in existence, until a 15-cent Z grill stamp was discovered, also with only two known stamps.
The first grill, now known as the “A” grill pattern, covered the face of the stamp; however, this made the stamps too fragile to be easily handled during production, leading to tears during perforation and other issues. The grill soon became a pattern pressed into a small area of the stamp, which was more successful. As different embossing equipment was tested, the pattern of the grille changed slightly, leading to the wide variety of grill types.
Grill types are designated by their size (the number of points on the pattern), which direction the points have been stamped (up or down), and which way the ridges lie (horizontal or vertical.) Points being “up” or “down” refers to whether or not the grill points are raised above the printed surface of the stamp, or sunk into it. The American Stamp Dealer relates a way of simplifying identification of stamp grills: “To make the tips of the pyramids show up, take an ordinary #2 lead pencil, turn the tip sideways and mark up a small area on a piece of scrap paper. Then rub the tip of your index finger over this area until the fingertip is covered with carbon. Then place the used stamp on a flat surface bottom side up. Now rub your finger over the grilled area of the stamp. This technique is best suited for grills with “Points Down” rather than for grill types A, B or C. The tips of the pyramids will pick up the carbon from your finger tip and will thus become more plainly visible. Once the task is completed, I use a simple “bath” in warm (not hot) water with just a drop of dishwashing liquid to make the stamp presentable once again. This technique is not necessary for those grills with ‘Points Up’ as the grill points should show up clearly anyway. Do NOT use this carbony technique on unused stamps that have any part of gum remaining.”
Grilled stamps are a fascinating remnant of a specific moment in our postal and technological history. It’s no wonder they are so highly prized!