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What is a Postage stamp made of?

What is a Postage stamp made of?
Coated paper with phosphor bands, printed in security inks, on either water-activated gum or a self-adhesive.

The switch to self-adhesives broke a century of philatelic practice. Collectors traditionally soaked used stamps off envelopes in warm water, which dissolves dextrin gum and leaves the stamp clean; acrylic pressure-sensitive adhesive does not dissolve, and soaking a modern stamp usually ruins it. The workaround is to cut the paper around the stamp and keep it on backing paper, or to use a citrus-based solvent. Perforations themselves were a Victorian invention — before 1854 clerks cut stamps apart with scissors — and the gauge of the perforations, measured in holes per two centimetres, is still one of the main ways a stamp is identified.

Component by component

Every material is a choice, and the third column is the constraint that drove it.
Part Material Why that material
paper coated wood-free paper, sometimes with fluorescent fibres A hard, coated surface takes the very fine engraved and gravure printing that makes a stamp hard to copy.
phosphor phosphorescent bands printed over or under the design Sorting machines find and orient the letter by these bands, and the number of bands used to encode the postage rate.
gum (traditional) dextrin or gum arabic Both are water-soluble starch or plant gums that stay inert dry and become tacky with a lick — and both are edible.
gum (modern) pressure-sensitive acrylic adhesive on a silicone-coated release liner Self-adhesives survive humidity that would make a licked stamp curl and stick to itself in the sheet.
security features die-cut simulated perforations, iridescent overprints, microtext A stamp is a bearer instrument worth real money, so it is printed with the same thinking as a banknote at a fraction of the budget.

Other stationery and paper objects

Common questions

What is a Postage stamp made of?
Coated paper with phosphor bands, printed in security inks, on either water-activated gum or a self-adhesive.
What is the paper of a Postage stamp made of?
Coated wood-free paper, sometimes with fluorescent fibres. A hard, coated surface takes the very fine engraved and gravure printing that makes a stamp hard to copy.
What is the phosphor of a Postage stamp made of?
Phosphorescent bands printed over or under the design. Sorting machines find and orient the letter by these bands, and the number of bands used to encode the postage rate.

Related pages

Sources

  1. Typical range compiled from manufacturer specifications — At One Place

How these figures are compiled and checked