Ink eraser
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A blotter or ink eraser , coll. And ink eraser , just killer , or older Tintentod called, is a pen to make corrections with usually only blue ink written texts. An ink eraser usually consists of two parts: one end of the ink can be made "invisible" and the correction can be made with the felt pen at the other end.
history
Even before 1900, industrially manufactured means for removing ink were generally known and commercially available under the names Eraserwasser and Tintentod . The first copies on the market contained the active substance as a pressed stick (similar to the razor pencils ). For use this was moistened and the ink was erased with it. The following products, such as the set consisting of two vials, sold under the Pelikan brand since around 1930, contained the active substance as a solution. This also includes the new pen, the ink killer , which came onto the market in 1972 as a trademark of the then Kreuzer company in Bonn. An identical model was later sold by Pelikan as an ink tiger .
Mode of action
All inks are organic dyes . They have a chromophore , a part of the molecule with freely moving electrons that can be excited by light of certain wavelengths . The incident light is therefore absorbed in this wavelength range . The light of the other wavelengths is reflected . The wavelength distribution changes with the (partial) reflection, which gives the reflected light a color . Triphenylmethane dyes such as water blue are mainly used as blue filler inks .
If the mobility of the coloring electrons is disturbed, the dye loses its color. In the case of triphenylmethane dyes, influencing the central carbon atom, for example with a nucleophile , is often sufficient.
Active ingredients
There are essentially three different methods known for the effect of the ink eraser:
- Quenching with sulfites: Here OH - and HSO 3 - ions attach to the central carbon atom of the dyes. Sodium sulfite (Na 2 SO 3 ), sodium hydrogen sulfite (NaHSO 3 ) or potassium sulfite (K 2 SO 3 ) , for example, are suitable for this purpose . The principle corresponds to that of the production of fuchsin sulfuric acid from fuchsin.
- Extinguishing with carbonates: Another, somewhat less effective option is interference with carbonates such as sodium carbonate (Na 2 CO 3 ) or sodium hydrogen carbonate (NaHCO 3 ). Here, too, OH - ions attach to the central carbon atom.
- Extinguishing with thiosulphates and dithionites: In addition to some more complex substances, dithionites or thiosulphates (e.g. Na 2 S 2 O 3 ) can also be used for ink killers.
In practice, these reducing agents are reinforced by other substances such as alcohol or soda (e.g. by the above sodium carbonate ).
Removing the erasing effect
As described above, the ink is not destroyed during the erasure process, but only made invisible. The reconversion into a visible form can be done with aldehydes or the vapor of about 36% hydrochloric acid . Another alternative is vinegar vapor with a corresponding concentration. By heating, if possible with hot air, the extinguishing effect can also be canceled to a certain extent. Even after a long period of time (several years, e.g. in old exercise books), the ink becomes partially visible again.
Magic pens and "secret ink"
Using the same principle, an ink killer can also be used to write secret messages that become visible when ink is applied over a large area with a thick brush and not too intensely. There have been special “magic pens” since the 1970s, which have a thin writing tip and a very thick, brush-like fiber tip with which a mostly invisible dye is applied over a large area, which only reacts in color with the “secret ink”. However, the term “magic pen” is sometimes used as a synonym for the ink killer itself. Lemon juice, certain fruit juices, and milk can also be used as home remedies for secret inks. The writing is usually visible when exposed to heat, as the substances mentioned then oxidize and a change in color, usually too brown, takes place.
Health hazard and alternatives
Rumors about the risk of cancer have their origin in formaldehyde , which was previously used as a solvent but was not part of the active substance. However, consumer advocates continue to warn against substances that are hazardous to health. If simply crossing out is not enough, the Stiftung Naturschutz Berlin recommends correction tapes or rollers (“mice”) as opaque colors. They are available on a water basis, some are even refillable or made from recycled plastic.
Individual evidence
- ↑ The company Aug. Leonhardi advertised with an advertisement in the German Literature Calendar for the year 1901, ed. by Joseph Kürschner, Leipzig 1901, before S. I u. a. for their product Tintentod (erasing water) . In the standard work The Proof of Forgery, Blood, Sperm, etc. Braunschweig 1906, p. 81, the authors Dennstedt and Voigtländer mention that these means are widespread and even used among school children.
- ^ Chemistry - environmental offenders felt pen & co. Student portal Lauftext.de
- ↑ Health and environmental protection for children. ( Memento of the original from November 19, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Consumer advice center NRW, August 2, 2016.
- ^ Writing instruments & Co. In: Stiftung Naturschutz Berlin (Ed.): School time - advice for an environmentally friendly start to school. 14th edition. 2013, ISBN 978-3-925302-38-1 , p. 20.
