An ink eraser is an instrument used to remove ink from a writing surface. There are two types: a traditional metal ink eraser, in which the ink is literally scraped off the surface, and the chemically imbued ink eradicator, in which a vinyl eraser is imbued with a substance that chemically reacts with the ink to hide it.
Metal ink erasers
Metal ink erasers were generally used before chemically imbibed ink erasers were introduced and when most writing was done in ink and not in pencil (or by computer). However, the erasers were essentially small knives, and by accident or purposely could end up as unlikely weapons in a stabbing.
In one instance in 1909, a 15-year-old boy working in an insurance office in New York City died when, while evading women stenographers trying to give him a kiss on his birthday, he fell and his ink eraser, supplied to office employees, stabbed his chest. In another instance, stemming from a bar fight in 1885, a man stabbed another with an ink eraser.
Chemical ink erasers
The chemical ink eraser was invented by the German manufacturer Pelikan in the 1930s, and was introduced as a novelty in Germany in 1972 under the name Tintenkiller (Ink killer).
Chemical ink erasers break down royal blue ink by disrupting the geometry of the dye molecules in ink so that light is no longer filtered. The molecules are disrupted by sulfite or hydroxide ions binding to the central carbon atoms of the dye. The ink is not destroyed by the erasing process, but is made invisible. It can be transformed back into a visible work with aldehydes.
It is to be noted that the eradicator works only with royal blue ink. It discolors black ink to a rust brown and changes the hue of non standard blues, limiting its usefulness.
Following companies have ink erasers:-
- "Stabbed to Death in Office Frolic," New York Times, February 16, 1909.
- "Bang Knocked Him Down: How Coles was Provoked to Stab Coachman Flanagan," New York Times, June 26, 1886.
- Prof. Blumes Tipp des Monats - Chemie des Tintenkillers
- This article incorporates information from the German Wikipedia.