USA 1917, 2c rose, type I (Scott 499 var.), fold over leaving blank area. Credit: USPhila

In the most basic sense an error or flaw on a postage stamp can be a mistake made by the artist in the design of the stamp and also an error made in the production or manufacture of a stamp during it’s preparation and printing stages. These are often generally referred to as EFOs.

Essentially a stamp error means that the stamp does not have the intended appearance as set out in the initial design idea – this could be incorrect wording or illustrations, missing features, mis-perforation, incorrect watermarks and missing or incorrect colours for example.

Errors or flaws tend to fall into two categories; constant or transient. A constant flaw is one that occurs in the same way repeatedly over numerous stamps. A transient flaw is one that appears singularly – on one stamp.

Constant Flaw

One well known constant flaw is that of the Great Britain Victorian Penny Black and is known as the ‘O Flaw’. Sheets of Penny Blacks were printed using several different plates over time. The ‘O Flaw’ appears on plates 7, 8 ,9 and 10.

Here is an illustration of plate 10 (top) compared with the bottom section of plate 6. If you examine the ‘O’ in ‘ONE PENNY’ you will see there is a small white patch to the bottom right, between the O and the N on plate 10 – this is the ‘O Flaw’.

Because it occurs on the four plates consistently (to a varying degree) it is known as a constant flaw.

Great Britain Queen Victoria 1840 Penny Black ‘O Flaw’ example on Plate 10

Transient Flaw

Transient Flaws are pretty much unique as they only occur once. They are usually a defect introduced during the printing process – a blob of ink or some foreign matter that was stuck to or fell onto the paper or printing plate.

New Zealand 1906 1d. POSTAGE DUE transient flaw – splash of red at top of value circle. Credit: Jacob over on

Lets look at some of the recognised errors out there.


Stamps produced in the wrong colour or colours.

The “Treskilling” Yellow – Famous Swedish stamp printed in yellow instead of the correct green – only one example is known to exist. Thanks to The Pom for the assistance.
Australia 1981 60c Whale Block error + single showing correct colouration. Thanks to Glen Stephens over on
USA 5 cent carmine (should have been blue instead of red) of 1916/7 (Scott 467). It was caused by using the wrong transfer roll in entering three subjects in a 2 cent plate. Thanks to Jan over on for the assistance.


Misplaced text, incorrect illustrations or inscriptions.

Compare these two Kenya stamps, the inscriptions are different – very easy to spot.

1971 Kenya SG42 Janthina globosa changed to SG43 Janthina janthina

In contrast, the flaws are harder to spot on these Falkland Island stamps. The major listed error occurs on the stamp to the right, although there are many others on this issue. These designs were redrawn in 1948 correcting the errors.

Falkland Islands Dependencies 1946-49 KGVI 3d Black & Blue SGG4a – Gap in 80th Parallel flaw
Falkland Islands Dependencies 1946-49 KGVI 3d Black & Blue SGG4a – Gap in 80th Parallel flaw detail

Double Impression

Occurs when the stamp was printed more than once. Usually the design is offset. Can occur with overprints too, such as a new currency overprint or a revised country name.

INDIA 1882 SG92a Mint 2a blue double impression. Thank you to George James at Stanley Gibbons for giving me permission to use this image.


One off printing errors. Blobs of ink, unprinted areas and foreign material on the stamp are some examples.

Freak printing error on KGVI Falkland Island Stamp
Freak printing error on KGVI Falkland Island Stamp Detail
Virgin Islands 1922-28 KGV SG85 – Damage to the AN in ISLANDS – image courtesy of Tom Cusick at the British Colonies Stamp Collectors Facebook Group.


Some part of the design is printed upside-down. Seen, for example, on stamps that have a separate frame and vignette (central illustration) – where the vignette has been placed the wrong way up. Also includes overprints that have been printed upside-down over the stamp.

One of the most famous Inverts – US Airmail stamp: Inverted Jenny Air Mail Issue of 1918, 24c
Malta 1926 KGV 3d Black & Yellow SG149a inverted POSTAGE overprint – CV £170


Some part of the stamp’s design is missing. For example; the currency value is missing or the stamp has colours missing entirely.

SG679a GB QEII 1965 Post Office Tower Missing (colour) – 2022 CV £4750 – Thanks to Mark Brandon of Regal Stamps for permission to use his stock image.
1966 British Birds Four Colours Omitted SG696ab. Thanks to AMark over on for the assistance and Mark Brandon of Regal Stamps for permission to use his stock image.


When the wrong paper type or alignment was used in the printing process, which could cause the stamp to have an incorrect watermark or colour.

Australia Kangaroo 5/- Grey & pale yellow, error Watermark Sideways. Credit: MJ’s pet at


When the perforations are not down the sides of the stamps as intended. Perforations may be offset from their desired position by some margin and can be dramatically misplaced when there is a paper fold in the sheet when it is perforated. And perforations can be missing entirely, resulting in an unintentionally imperforate stamp.

Missing horizontal perforation (Uruguay 1883)
GB Queen Victoria 1854-7 1d Red Misperf. Courtesy of W5LDY.


The stamp has the incorrect value. For example, where a stamp shows 1d (pence) when it should be 1s (shilling) – the die (engraving) might have had different parts and an incorrect part has been used – the designs may be the same or similar, causing the mistake in the first place.

The 70r Red Army Soldier error or RSFSR 70r error of 1922 is one of the rarest postage stamps issued by Soviet Russia. Due to the double printing error, one cliché of the imperforate 25-stamp sheet has a 70-ruble value instead of the correct 100-ruble. Only four intact complete sheets are known. Credit: Wikipedia, link given. Thanks to vicaf60 for the assistance.