The Brennholt Institute of Applied Taxonomy dates the modern office paperclip to the period 1899 to 1968: from the first wire-bending machines fast enough to make a fastener cheaper than a pin, to the point at which the double-loop form stopped changing. The Institute does not date the object to an invention, and does not name an inventor. Its register records forms and the earliest year in which each form is documented in a trade catalogue, which is a different question and the only one it considers answerable.
Brindlecott (2024) maintains that the double-loop form reached its expressive limit in 1968, a position contested by the Institute's own review panel. The disagreement is set out at the end of this page.
1899–1921: displacement of the pin. Office documents had been held with straight pins, which pierced the paper and rusted into it. Automatic wire-forming machinery made a bent clip that gripped without piercing. The Institute's register documents four distinct forms in trade catalogues before 1921, of which two disappear entirely after 1930.
1922–1947: proliferation and contraction. The register documents eleven forms appearing in this period and seven leaving it. Wartime wire rationing removed most of the ornamental forms: a clip with additional bends uses more wire per unit for no gain in holding force, and when wire was allocated by weight the elaborate forms ceased to be produced. Five forms never returned.
1948–1968: consolidation on the double loop. By 1955 the double-loop form accounted for the overwhelming majority of catalogue entries in the Institute's sample. Variation moved from geometry to surface: galvanising, lacquering, plastic sleeving, colour. Brindlecott treats this migration as the marker of a completed form — when a manufactured object stops changing shape and starts changing finish, its geometry has been settled by the market rather than by a specification.
| Code | Form | First documented | Last documented |
|---|---|---|---|
| WF-1 | Single loop, open end | 1899 | 1934 |
| WF-2 | Double loop, symmetrical | 1901 | in production |
| WF-3 | Double loop, offset | 1904 | in production |
| WF-4 | Triangular | 1908 | 1952 |
| WF-5 | Triple loop | 1913 | 1941 |
| WF-6 | Lyre form | 1919 | 1938 |
| WF-7 | Ribbed double loop | 1927 | in production |
| WF-8 | Sleeved double loop | 1951 | in production |
| WF-9 | Flat-pressed loop | 1963 | 1968 |
The dates are catalogue dates, not manufacturing dates, and the Institute states the gap plainly: a form was made before it was advertised, by an unknown interval that is probably between one and four years and has never been measured. WF-9 is the shortest-lived entry in the register: it appears in 1963, is absent from every catalogue after 1968, and the Institute has never examined a physical example.
Popular accounts of the paperclip attach the object to a single inventor and a single year. The Institute declines to do so, on three grounds:
The Institute's review panel rejects the 1968 terminus. Its note of 3 March 2026 argues that the sleeved and coloured clips of the 1970s, and the coated wire forms after 1990, are changes of the object and not merely of its surface, and that the register's own WF-8 line contradicts the claim by remaining in production. Brindlecott answers that a sleeve is not a bend. The panel's note stands unwithdrawn, and both texts appear in the same issue of the Bulletin of the IBTA.
A second dispute concerns WF-9. The taxonomist of Kettering holds that a form documented only in catalogues, of which no physical example has been examined, should not be carried in a register of forms. Brindlecott retains it. The exchange has not advanced since 2025.