GRILLS ON POSTAGE STAMPS
The grill consist of small square pyramids in parallel rows, impressed or embossed on the stamp. The object of the process is to break the fibers of the paper so that the ink from the cancellation would soak into the paper and make washing for reuse impossible. Grill impressions, when viewed from the face of the stamp, may be either "points up" or "points down".
CLASSIFICATION OF GRILLS
A Grill - Covers the entire stamps B Grill - 18 x 15 mm C Grill - 13 x 16 mm D Grill - 12 x 14 mm Z Grill - 11 x 14 mm E Grill - 11 x 13 mm F Grill - 9 x 13 mm G Grill - 9 1/2 x 9 mm H Grill - 10 x 12 mm I Grill - 8 1/2 x 10 mm J Grill - 7 x 9 1/2 mm