1, space pen
The space pen, also known as the pressurized ballpoint pen, is a novel technology. Take the Fisher Space Pen as an example. The space pen's refill is pressurized (~0.28 MPa), and its ink is a special viscous ink (like viscous rubber glue). To make a viscous ink liquid, the ball must be rotated so that the ballpoint pen can be smoothly written on most surfaces or even underwater. Ordinary ballpoint pens rely on gravity to supply ink, and there is an opening above the refill that allows air to replace the used ink. The space pen has no holes, which avoids evaporation and waste of ink, and also prevents ink from leaking from the back of the refill. In addition, the space pen can last up to 100 years, compared to an average of two years for ordinary ballpoint pens.
Since the beginning of the "space race" in the 1960s, space pens have been used by American astronauts in all manned space flights, including the moon landing project. In addition, they are used by many Russian astronauts in the Soyuz space flight and the Mir station.
2, erasable ballpoint pen
The erasable ballpoint pen was introduced in the early 1980s and was very popular at first. They combine the readability of bright color or black ink with the erasable function of a pencil. Although the ballpoint pens are still produced under the banner of brands such as Gillette Eraser Mate, they are not as popular as they used to be. These ballpoint pens are described in detail in patent documents such as US 2,966,418 and US 4,097,290. What makes an erasable ballpoint pen unique is its "ink" - it is made of liquid rubber glue instead of oil and dye. As you write, the ball rolls and releases the rubber glue ink onto the paper (the resulting trace is called the trajectory). Modern erasable ballpoint pens leave a clear, thick black or colored trajectory on the paper that looks like ordinary ink, but can be easily erased shortly after writing (usually up to 10 hours). After that time, the track will harden and become non-erasable. The ink of the erasable ballpoint pen generally contains 15% to 45% by weight of natural rubber which is dissolved in a series of volatile organic solvents having different boiling points.