User Manual

Product information
Erasers - Sharpeners
1 Erasers
Not every eraser has the same erasing performance to offer. There are different erasers
available especially designed to meet the requirements of different writing instruments
(blacklead pencils, coloured pencils, fountain pens and technical pens).
The performance of an eraser is dependent on whether the mark to be erased is only on the
surface or whether it has already penetrated deeper into, e.g., the paper.
In the case of pencil marks, for example, erasers remove the graphite by means of adhesion
(accumulation) leaving the paper undamaged. During the erasing process the dirtied eraser
surface gets abraded.
However, ink marks penetrate paper; this means that an eraser is required which actually
removes the top layer of the paper.
By varying the formula, different types of erasers can be manufactured.
1.1 Requirements
Excellent erasing results
Minimal crumbling
No smudging
No discolouration caused by hand perspiration
Clean and easy handling, e.g. eraser sleeves
No aging even after long storage times
1.2 History
The history of the eraser began back in 1770 with a discovery made by the English chemist
Priestly. He found out that rubber was a good material for cleaning paper with and that it could
also be used for removing pencil marks without damaging the surface of the paper.
The American Charles Goodyear managed to improve the characteristics of rubber by mixing it
with powdery substances. Furthermore, he discovered that by adding sulphur and by exposing
the mixture to higher temperatures, a product could be created that had much better product
properties and was more resistant to heat than was the case with raw rubber. In 1843 he
registered a patent for this so-called “vulcanisation” process.
This was the foundation upon which, at the end of the 19
th
century, German and American
companies began to base the development of natural rubber erasers such as we know them
today.
 2002 STAEDTLER MARS GmbH & Co. Page 3 of 13
version 07. 2002 subject to change
Further developments included replacing the natural rubber content by other elastomeres
(polymers with rubber-elastic characteristics) which offer better features such as longer storage
life and superior erasing accuracy.