To separate postage stamps from one another, old problem. Cut with scissors, pre-separate them with points, lines or perfortations... In the first decades of the postage stamp history, inventors and clients looked for practical solutions. Today, again, the matter is still interesting.
Very certainly, the whole United States' philatelic program is now self-adhesive: on sheets, booklets, rolls of hundreds of stamps.
On this postcard, the ondulated line helped to detach easily the stamp from its backsheet. On the left handed stamps, from the Flags of the States series designed by Tom Engeman, one of most favourite illustrators of the USPS, the horizontale line separates the two stamps. Even if on the lower right and upper left of Iowa and upper right of Illinois, a tiny bit of paper connects them though (around one millimiter in length).
British side, the new Reinforced Security Machin stamps (or "with security features") are not celebrating their first month that variations have already appeared. The oval slits must render impossible to detach the used stamp from the cover. Ian Billings constated that the slits are two semi-ovals on stamps from sheets, but four quarters of oval on the stamp from the commemorative booklet to be issued on 10 March (linked to the "Design Classics" issue).
A tiny bit of paper again. Is this a second type of this stamp that will be permanent on stamps printed by Walsall? An error in the sliting and that will be quickly corrected?
The Machin series, a always renewed sage: here, again, don't forget...