The ballpoint pen - the writing instrument for all occasions
Some people believe that the ballpoint pen was invented by Nasa for the space program because ordinary fountain pens do not work in weightlessness. But that's not true. The "space pen" was developed for astronauts, and its refill is pressurized with nitrogen so that the writing ball is always wetted with ink. But the original patent for the ballpoint pen was registered in 1943 by László József Bíró in Argentina.
Since then, the ballpoint pen has triumphed around the world and it is hard to imagine any office, briefcase or pencil case without it. But what makes the ballpoint pen so superior to other writing instruments, such as a fountain pen?
Liquid ink has a precise, high-contrast typeface and a buttery smooth feel when writing. That alone makes them superior to a pencil. However, it is not particularly comfortable to use: In the past, the nib had to be dipped into the ink bottle after a few words, a procedure that was later made superfluous by piston-action fountain pens. It was not until the invention of the ink cartridge, which is now standard in all school pens, that a fountain pen became truly convenient to use. But all generations of fountain pens share one problem: the ink is and remains liquid - and thus these writing instruments can cause ink blots on the paper or, in the worst case, leak, which makes a huge mess.
These are exactly the problems the ballpoint pen was designed to solve: An ink-based pen that neither spills nor leaks! Instead of liquid ink, the (easily replaceable) refill of a ballpoint pen is filled with an ink gel that is simply too tough for that. Of course, this gel cannot be used with a classic nib; instead, there is a metal ball in the tip of the pen that rolls over the paper on the front side while absorbing gel on the back. On the one hand, the ball transports the ink onto the paper, but at the same time it serves as a seal for the refill. An ingenious idea!
At least in theory, because everyone has certainly experienced that a ballpoint pen can also leak (even if very rarely). In fact, however, this is rarely due to the pen itself. Of course, there are inferior cheap models where the ink is too fluid or the writing tip has too high tolerances. Then the ink very easily finds a way out!
Usually, however, this only happens if either the tip is damaged, for example after a fall - or if the ink becomes too warm: As the temperature rises, the gel increasingly liquefies, and then the sealing effect of the ball is simply no longer sufficient. This often happens in summer, especially in the breast pocket of a shirt or the inside pocket of a jacket. If the sun then comes into play, the scenario for a drama is perfect. However, the likelihood of a refill failing decreases drastically with increasing quality: High-quality ballpoint pen refills are much more temperature-stable than super-cheap models. The trick is to adjust the viscosity of the writing gel in the refill so that it is fluid enough not to cause writing misfires - but tough enough (even at somewhat higher ambient temperatures) not to leak. This requires a little more development work and a high degree of precision in manufacturing! Anyone who buys refills for ballpoint pens in a 5-pack for 1 euro should not be surprised if these requirements are not met.