How are stamps printed and made?
Australian stamps are printed using a process called offset lithography. Offset printing is fast, and ideal for producing large quantities of printed material. Our stamps are very colourful but most of them are printed with only four coloured inks, in a system called CMYK: cyan (bright blue), magenta (pink), yellow and black. Play the How stamps are printed – CMYK animation below.
When different percentages of each colour are combined, they produce the wide range of colours we see on our stamps. All four colours are printed on a stamp in a single operation. If you look closely at a stamp that has been printed with this four-colour process, you can see that the picture is made up of a pattern of tiny coloured dots.
Play the How stamps are made video below to see how stamps are printed and packaged for sale.
We want proof!
The first few sheets to be printed are called "proofs". The proofs are inspected closely for any errors or colour variations before the final printing begins and any faulty sheets are destroyed. The large sheets are then perforated and cut into smaller sheets for delivery to Australia Post retail outlets.
Part of every stamp is invisible to our eyes, and can only be seen by Australia Post's sorting machines. A special phosphorescent coating that shows up under an ultraviolet light is applied to each stamp. This light is what the sorting machine uses to position the stamp for cancellation (postmarking) when a letter is sorted for delivery.
What year was that?
Australia Post has been printing the year of issue on stamps since 1989. It's usually very tiny, so it doesn't spoil the design. Get out a magnifying glass and see if you can find the date on your stamps.
Many old stamps were printed using an engraving process called "intaglio". Engravers were highly skilled craftspeople.
They etched the design into a flat metal plate, using lots of finely spaced lines to produce different shades. Originally this was all done by hand!
Lick or stick?
Stamps can be printed on gummed paper that you have to lick or dampen so they stick to an envelope but nowadays four out of five of all stamps printed are self-adhesive. These stamps stick much better, so a special paper had to be developed for Australia Post – so you can still soak stamps off envelopes for your collection!
The large sheets of stamps are perforated for easy separation. Perforation is achieved by punching small holes between the stamps using hard steel pins called "combs". Self-adhesive stamps are made to peel off a backing sheet but they still have the same perforated appearance.
Early stamps had no perforations; they had to be cut from the sheets with scissors!