Stamp sheets are normally perforated so that individual stamps can be separated easily from one another and from the sheet. Stamps without perforations along their edges are described as imperforate or unperforated. The world’s earliest postage stamps, including the Penny Black, were issued without perforations and had to be cut from the sheet with scissors. Because this was inconvenient, Great Britain introduced the first perforated stamps in 1854, after which stamps without perforations became unusual.

In strict philatelic terminology, an imperforate stamp is one that was intentionally designed and issued without perforations or rouletting. The Penny Black is a classic example, as are Hungary’s newspaper stamps issued between 1874 and 1899. By contrast, stamps whose normal issue was perforated but which also exist without perforations are more precisely described as unperforated varieties . In everyday collecting language, however, the distinction is often blurred and both are commonly referred to simply as imperforate stamps.

How did unperforated stamps enter circulation?

1. As production errors. On rare occasions the perforating stage was omitted and the error escaped inspection, allowing complete unperforated sheets to enter postal circulation. Examples include the 10 and 25 fillér values of the 1900 Turul issue and the 30 fillér value of the 1909 issue. Such production errors are major rarities and can be highly valuable.

2. From retained printing stock. The Royal Hungarian Post kept small quantities of technically finished but still unperforated sheets and some progressive proofs, sometimes for presentation or propaganda purposes. Many of these imperforate sets and souvenir sheets later became available to collectors. The Catalogue of Hungarian Stamps lists and values such material from 1909 onward.

3. Through unauthorised removal from the printing works. Unperforated proofs occasionally left the printing works illegally. One example is the 30 fillér value of the 1943 Military Leaders issue, of which a large quantity escaped in this way; as a result, its present market value is relatively low.

4. As official collectors’ issues. Under Instruction No. 180.633/8.B. of the Directorate-General of Posts, issued in 1958, imperforate versions of stamps then in use and of subsequent issues could also be used for postage. Small quantities were occasionally sold at face value at selected post offices, while larger quantities were made available to organised collectors at multiples of face value and could be purchased by anyone at still higher prices.

This did not apply to stamps and souvenir sheets that were genuinely issued imperforate—such as Bethlen, Pushkin, Stalin, UPU and Haydn–Schiller—which were sold on terms similar to their perforated counterparts.

The Hungarian Post discontinued the parallel issue of low-print-run imperforate versions at the end of 1991. From 2014, however, it reintroduced imperforate versions for selected issues, mainly souvenir sheets, such as the 2014 Miklós Ybl, 2014 Return of the Seuso Treasure and 2015 Miksa Róth issues. These modern imperforate versions are no longer valid for postage.

Imperforate and unperforated varieties are identified separately in stamp catalogues.

Imperforate varieties were usually produced in much smaller quantities than their perforated counterparts and are therefore generally considerably scarcer and more valuable. Their market value is often many times higher and in some cases may be 10–15 times that of the perforated version. The difference may, of course, be smaller or larger depending on the issue. Catalogues value these varieties separately, and their prices are also shown in the descriptions of the relevant issues.

The image above shows the imperforate version of the 1955 Transport and Industry set. A total of 560,800 perforated sets were produced, compared with only 2,500 imperforate sets. This difference in quantity is naturally reflected in their market values, with the imperforate set commanding a substantially higher price.

Because of the large difference in value, imperforate stamps have also been forged by trimming the perforations from ordinary perforated examples. Such forgeries, made to deceive collectors, can usually be recognised by margins that are narrower than normal.