How long is the shelf life of rubber?

The shelf life of eraser depends on the composition of rubber, but the durability of most consumable rubber materials will not exceed 4 years. Eraser is a kind of thing with good surface quality and coating, which can be preserved for a long time without grinding. If the cylindrical surface is covered with a protective layer (like a pencil), it can be used from beginning to end without any sensory attenuation.

Historical source

In 1770, joseph priestley, a British scientist, said: I saw a substance that is very suitable for erasing pencil handwriting.

At that time, the whole of Europe used rubber particles cut into small cubes to erase handwriting. This substance is called an eraser.

Edward Gnehm, another British engineer, is believed to have invented the eraser in 1770. Before that, people used bread crumbs to erase handwriting. Naimei said that once he accidentally picked up a rubber as bread crumbs, but found that the effect was very good, so he began to produce and sell rubber.

The original eraser was inconvenient, because the unprocessed eraser was easy to rot. Until 1839, inventor? Charles Goodyear found that vulcanization can improve the quality of rubber, so the eraser became reliable.

1858, a man in Philadelphia, USA, obtained a patent for embedding an eraser at the end of a pencil. However, the patent of this pencil with eraser was later revoked because it was judged as "just embedding two existing things together, not a new product".

The English name of eraser is in Britain and Australia, and eraser is called eraser. ; But in America, rubber is one of the common names of condoms, and the name of eraser is eraser. This difference is often regarded as a joke by Americans.