24 gen 1884 anni - Carborundum is a very hard mixture consisting primarily of silicon carbide; it is used as an abrasive and, in powdered form, in a method of engraving invented by Henri Goetz. He used it to get a dotted effect by sprinkling it over a metal plate which was then pulled through a press, which got the grains to push into the metal.
Aggiunto al nastro di tempo:
Data:
24 gen 1884 anni
Adesso
~ 140 years ago
