Bíró used gravity and a rolling ball to feed thick ink

Writing in ink meant fighting the pen. Quills had to be re-dipped. Fountain pens, the refinement of the late nineteenth century, still blotted, smeared and clogged, and ran on thin, slow-drying ink that never quite dried. László Bíró, a Hungarian journalist in the 1930s, noticed that the ink used to print newspapers offered a clue: it dried almost immediately, leaving the page clean and smudge-free.

He tried putting that quick-drying ink in a fountain pen and it would not work at all. The ink was too viscous, so it would not flow into the nib, and a nib that fed thick ink either blocked or coated the page in blobs. He worked with his brother Georg, a chemist, and the breakthrough was to change how the ink reached the paper rather than to thin the ink.

Bíró's device was a metal ball that sat loosely in a socket at the tip of the pen. As the ball turned, it picked up ink from the reservoir above it and rolled it onto the paper, while gravity and capillary action kept the ink flowing. The design needed no pressure to drive the ink and could handle the thick, quick-drying ink that a fixed nib could not. His early designs used mechanical pressure to force the ink, but the gravity-fed version succeeded in 1943 once better parts and ink made it reliable.

He patented the idea in Budapest in 1938 and later in several countries and the United States. The design that emerged is essentially the pen still used today, and it worked far better than fountain pens at altitude, which is why it was licensed in Britain for Royal Air Force aircrew. In 1945 Marcel Bich bought the patent and turned it into the Bic company's core product.