Ebonite
The Ebonite (often called hard rubber or also vulcanite in some old advertisements) is a material invented[1] in 1843 and produced by a rubber vulcanization process in which the natural rubber is mixed with a variable percentage (from 20 to 50%) of sulfur, and hardened by keeping it at high temperature for a prolonged time (a few hours around 150°C). Hard rubber is generally produced in sheets, bars or slabs, which must be subsequently processed; in fact, it is not possible to make it with a mould.
Ebonite is a hard and brittle material, very resistant to corrosion by acids, and softens when heated. It is an excellent electrical insulator. It is easy to process and has been used both for the construction of objects and as an electrical insulator (use that still holds today). It owes its name[2] because it was initially used as a substitute for ebony. Its chemical resistance characteristics have seen it used for many years as an insulator, coating for corrosion-prone parts and as a battery case for cars.
Ebonite is the first material used for the production of fountain pens, in use since the first examples produced at the end of 1800. If even some objects considered as "precursors" of the fountain pen were made of metal, the first fountain pens were born substantially as a result of the invention of this material, which with its characteristics of ease of use, chemical inertia (and consequent resistance to corrosion), proved to be optimal for the construction of that "reservoir" of ink that was in fact the main component of the first fountain pens, and this also thanks to its characteristics of thermal insulation, which avoid the transmission of heat from the hand to the air of the reservoir, with a consequent increase in pressure and loss of ink.
The material, however, suffers from high mechanical fragility, which makes the ebonite pens not very resistant to shocks and falls, in this case the chemical neutrality proves a defect as it makes it almost impossible to glue pieces of ebonite together in a resistant manner.[3] Furthermore, with exposure to light, humidity and heat, the sulphur present in the material tends to oxidise, and to emerge on the surface, colouring it with a sort of dark brown opaque film that removes the lustre of the original polish. This patina is an indication of the age of a pen, and even if today there are products that can reverse the process and bring the material back to its original shine, the opportunity for such an operation is questioned by those who do not consider it respectful of the state of the pen.Errore nelle note: </ref> di chiusura mancante per il marcatore <ref> Questo ha dato luogo a diverse lavorazioni, dalla classica ebanite rossa, alle varie combinazioni fra ebanite rossa e nera (Mottled, Rippled, ecc.) fino alla produzione, portata avanti sostanzialmente dalla sola Waterman[4] nella sua ostinazione a non abbandonare questo materiale, di colori come il verde, l'azzurro, il giallo ed il rosa. Ma alla fine nessuno di questi colori poteva competere con la brillantezza offerta dai nuovi materiali, ed in particolare dalla celluloide, e l'ebanite è stata progressivamente abbandonata come materiale usato per il corpo della penna, restando impiegata però fino ai nostri giorni nella produzione degli alimentatori.[5]
Note
- ↑ see the italian and english entries of Wikipedia, which, however, present some discrepancies, in particular on the attribution of the invention to O. Meyer and T. Hancock for the first and Charles Goodyear for the second.
- ↑ the "ebonite" one, still beeing much more commonly called "hard rubber" as "ebonite" was a trade name.
- ↑ see this discussion.
- ↑ anche se sono noti modelli Tibaldi in ebanite colorata.
- ↑ anche se oggi questo avviene solo per le penne di maggior pregio, dato che questo materiale non può essere lavorato a stampo.