||The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (December 2010)|
A grill on a postage stamp is an embossed pattern of small indentations intended to discourage postage stamp reuse. They were supposed to work by allowing the ink of the cancellation to be absorbed more readily by the fibres of the stamp paper, making it harder to wash off the cancellation.
In the United States
The best-known (indeed only major) examples of grilling are the United States issues of the late 1860s and early 1870s, when grilling was standard for all US stamps. "Grilling" therefore remains a specialist interest only for American philatalists. While many types of grilled stamps are common, certain of the grill patterns were little-used, and define some of the great rarities of philately. In particular, the 1-cent stamp with the "Z" grill is generally cited as the rarest of all US stamps (only two copies are known), and is commonly known simply as the Z Grill. A recently discovered grill issue, the 30-cent "I" grill stamp, may be even rarer, for only one example has thus far been identified.
The first type of grill to be tried, termed by philatelists the "A" grill, was applied to the entire stamp. Stamps so treated were distributed to post offices for testing in August 1867, and apparently satisfactory, as National received a contract stipulating use of grilling for all stamps. However, the actual practice of grilling on a large scale had not been completely worked out, and the process significantly weakened sheets, resulting in tearing during perforation and general production handling. National soon switched to the use of a small rectangular pattern of indentations, and subsequent grills were all of this form.
National's contract did not specify the type of grill pattern, and the details changed as they experimented with equipment. Many of the details have been lost to history; in 1910s, philatelist William L. Stevenson introduced a system of distinguishing types of grills, and identifying them by letter. Later research clarified some of the details of chronology.
No G, H, I or J grills are found on the 1861-68 issue, for this series went out of production before they were introduced. The 1869 issue used only the G grill, while the 1870 issue used H and I grills. Fears of reuse had abated by the early 1870s, and grilling seems to have been quietly dropped from the production process. Some stamps of the Continental Bank Note Company (who took over production from National) are known to have been impressed with the "J" grill as late as 1875.
- A Grill - overall (first experimental grill)
- C Grill - points up, 16-17 x 18-21 points (second experimental)
- Z Grill - points down, points with horizontal ridges, 13-14 x 17-18 points
- D Grill - points down, vertical ridges, 15 x 17-18 points
- E Grill - points down, vertical or "X" ridges, 14 x 15-17 points
- F Grill - points down, vertical or "X" ridges, 11-12 x 15-17 points
- B Grill - points up, "X" ridges, 22 x 18 points
- G Grill - points down, vertical ridges, 12 x 11-11.5 points
- H Grill - points down, vertical ridges, 11-13 x 14-16 points
- I Grill - points down, vertical ridges, 10-11 x 10-13 points
- J Grill - points down, vertical ridges, 9-10 x 12 points
The least-widely used of these patterns (all associated with the 1861-68 issue) were the "B" and "C" Grills (both found on only the three-cent denomination), the "D" Grill (found only on the two-cent and three-cent denomination) and the "A" Grill (found only on the three-cent, five-cent and thirty-cent denominations). The rarest grilled U. S. stamps are:
- thirty-cent I Grill (1 surviving copy—see note below)
- one-cent Z Grill (2 surviving copies)
- fifteen-cent Z Grill (2 surviving copies)
- twelve-cent I Grill (2 surviving copies—see note below)
- ninety-cent I Grill (3 surviving copies—see note below)
- three-cent B Grill (4 surviving copies)
- five-cent A Grill (4 surviving copies)
- ten-cent Z Grill (6 surviving copies)
- thirty-cent A Grill (8 surviving copies)
Note: Given that intensive studies of the I Grill began only recently, additional copies of the I Grill issues listed here may well be discovered in the future.
Although the National Banknote Company ceased to issue U. S. Stamps after being supplanted by Continental in 1873, it soon began to produce stamps for Peru, on a contract that stipulated the use of the grilling process. Grills of three different types appear on regular issue stamps of Peru produced between 1874 and 1884. One of these Peru grills displays the horizontal ridges that characterize the American Z grill, but the Peruvian version is smaller in size, measuring 9 x 14 mm. The other two grills measure, respectively, 11 x 15½ mm. and 10 x 12 mm.
- Z Grill The Benjamin Franklin Z-Grill 1c stamp 1868.
- Classification and photos of grills of U.S. stamps
- Siegel Auction Galleries - 1867–68 U.S. Grilled Issues
- Bennett, Russell and Watson, James; Philatelic Terms Illustrated, Stanley Gibbons Publications, London (1978).