Do you know how to remove stains?
1. Immerse the stained area in warm water (40°C), rub it with benzene or a cotton ball dipped in benzene, then wash it with detergent and rinse with clean water (warm water).
2. Soak the stained area with cold water, wipe it lightly with carbon tetrachloride or acetone, wash with detergent, and rinse with warm water.
3. When the stain is deep, wipe it with gasoline first, and then rub with 95% alcohol. If there are still traces, it needs to be cleaned with bleaching powder. Finally, rub it gently with toothpaste and soap, and then rinse with water. But it is strictly forbidden to use boiled blisters. 4. If it is stained on paper, it is most suitable to use correction fluid or correction tape.
There have been some more interesting developments in the field of ballpoint pens, two of which are space pens and erasable ballpoint pens.
1. Space pen The space pen, or pressurized ballpoint pen, is a novel technology. Take the Fisher Space Pen as an example. The pen core of the space pen is pressurized (~0.28MPa), and its ink is a special viscous ink (like viscous rubber glue). To turn the viscous ink into a liquid, the ball must be rotated so that the ballpoint pen can write smoothly on most surfaces and even under water. Ordinary ballpoint pens rely on gravity to supply ink, and there is an opening above the refill so that air can replace the used ink. The space pen has no small holes, thus avoiding the evaporation and waste of ink, and also avoiding ink leakage from behind the refill. In addition, the lifespan of a space pen can be as long as 100 years. In contrast, the average shelf life of an ordinary ballpoint pen is only two years. Since the start of the "Space Race" in the 1960s, the space pen has been used by American astronauts in all manned space flights including the moon landing project. In addition, they are also used by many Russian astronauts during the Soyuz space flight and on the Mir space station.
2. Erasable ballpoint pen Erasable ballpoint pens were introduced in the early 1980s and became popular at first. They combine the legibility of bright color or black ink with the erasability of a pencil. Although these 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. Patent documents such as US2966418 and US4097290 describe these ballpoint pens in detail. The distinctive feature of the erasable ballpoint pen 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 traces are called trajectories). Modern erasable ballpoint pens leave clear, thick black or colored traces on the paper. These traces look similar to ordinary ink, but can be easily erased shortly after writing (usually up to 10 hours). After that time, the track will harden and become indelible. Erasable ballpoint pen inks generally contain 15% to 45% (by weight) of natural rubber, which is dissolved in a series of volatile organic solvents with different boiling points.