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 before. Patent documents such as US2966418 and US4097290 describe these ballpoint pens in detail.
What distinguishes 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 trace is called a track). 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.
