How a ballpoint pen works
A tiny ball, a thick ink and a clever idea: why the ballpoint became the world's most common pen.
The ballpoint pen is so common that nobody thinks about it. Yet inside the tip is a clever bit of engineering, and getting it to work took years.
The basic idea#
At the end of the pen is a tiny metal ball, held in a socket. As you write, the ball rolls across the paper. As it turns, it picks up ink from the reservoir behind it and rolls it onto the page.
The ball does two jobs at once. It acts as a valve, keeping the ink in when you are not writing, and as a roller, delivering ink when you are.
Why the ink is thick#
Fountain pens use thin, watery ink. That would leak straight out of a ballpoint. Ballpoint ink is a thick, oil-based paste that stays put until the ball turns. It also dries fast, which is why it rarely smudges and why the pen can sit in a bag without leaking.
A long history#
Early attempts at a ballpoint go back to the late 1800s, but the ink and the tip were never reliable. In the 1930s a Hungarian journalist named László Bíró, working with his brother, developed a practical version using the thick, fast-drying ink similar to the kind used in newspaper printing. He patented it in 1938. Ballpoint pens were later made in huge numbers and became cheap enough to give away.
Why it succeeded#
- It does not need refilling often. One cartridge can write for a very long distance.
- It works on most paper.
- It is cheap and durable.
- It can be carried in a pocket without leaking.
A tip#
If a ballpoint skips or stops, try scribbling in small circles on scrap paper. That often gets the ball turning and the ink flowing again.
A good deal of design is invisible. The ballpoint is a fine example of something so well made that you never notice it.