László Bíró patents the modern ballpoint pen

Frustrated by fountain pens that smeared and ran dry, Hungarian journalist László József Bíró noticed that the ink used to print newspapers dried almost instantly. The catch was that this thick ink would not flow through a conventional nib. His solution was a tiny rotating ball seated in a socket at the pen’s tip: as the ball turned against the paper, it picked up viscous ink from a reservoir and laid it down in a clean, fast-drying line.

Having fled Europe for Argentina, Bíró refined the design with his brother György. On 17 June 1943 he filed the application that issued as US Patent 2,390,636, “Writing Instrument” — the foundation of the modern ballpoint. It claimed a priority date of 17 April 1943 in Argentina and was granted on 11 December 1945.

The ball, not the ink, was the breakthrough — it metered just enough to write without flooding the page.

Marketed in Argentina as the birome, the pen spread worldwide and, in Britain, lent Bíró’s name to the everyday word for it: the biro.