Wafer pressing
A waffle impression on postage is a security measure against repeated use of the stamp. In these stamps was passed through a Gaufrage a waffle-shaped pattern ( English grill imprinted) which should receive the stamp ink better. The fibers of the paper were broken through, the stamp ink could penetrate there better and the washing off of the ink was made more difficult. This safeguard was in place on postage stamps from the United States in the 1860s and 1870s and soon after in Peru .
The grid types of the USA have been classified according to the chronological appearance according to the alphabet by William L. Stevenson. There were already attempts to classify them before that, but the Stevenson system has been the standard ever since. Stevenson himself had put together a reference collection that was donated to the New York Public Library through a few intermediate owners.
| Type | Size in millimeters |
|---|---|
| A grill | the whole area |
| B grill | 18 × 15 |
| C grill | 13 × 16 |
| D grill | 12 × 14 |
| Z grill | 11 × 14 |
| E grill | 11 × 13 |
| F grill | 9 × 13 |
| G grill | 9.5 × 9 |
| H grill | 10 × 12 |
| I grill | 8.5 × 10 |
| J grill | 7 × 9.5 |
The best known type is the Z grill . Stevenson didn't recognize this type until later, so it's not in alphabetical order. The oldest type is the A grill, with the entire stamp area. After it was determined that the A grill damaged the marks too much, only smaller rectangles were imprinted instead of the total area.
Individual evidence
- ↑ James Mackay: Philatelic Terms Illustrated. Publisher: Stanley Gibbons Ltd, London and Ringwood 2003, ISBN 0-85259-557-3 , p. 64
- ↑ See WM. L. Stevenson: United States Grills , Severn-Wylie-Jewett Co., Publishers Mekeel's Weekly Stamps News, USA, Handbook Number Sixteen, ca.1916, 15 pp.
- ↑ a b Ken Lawrence: The 1-cent grill mystery. In: Michel Forand (editor): The Congress Book 1995 (book for the 61st American Philatelist Congress), pp. 1–25