Hard rubber was the first man-made plastic of the industrial era. The key difference between hard rubber and regular rubber is the larger quantity of sulphur used, which also necessitates a considerably longer period of vulcanization. Hard rubber was first produced in the 1850s; early applications included buttons, combs, jewelry, and a broad range of personal articles.
Ebonite bracelet, c. 1860
Its resistance to chemicals made it useful for industrial applications, such as the lining of vats, and its ability to be molded and machined made possible the large-scale manufacture of scientific and medical devices that formerly had to be crafted individually out of metal and glass. Mass production of fountain pens would not have been possible prior to the availability of hard rubber.
Hard rubber inhaler
Day's patent pencil, c. 1860
Although experiments with coloring agents started almost immediately, it is uncommon to find old hard rubber stock in any color other than black. Red (orange) hard rubber proved to be quite brittle, so most vintage colored hard rubber consists of a mixture of red and black, usually in a woodgrain or mottled pattern. Modern hard rubber is available in a much broader assortment of colors and patterns; all tend to be muted in hue, and all are opaque. Hard rubber can be polished to a brilliant shine, but will fade with exposure to bright light. This is more of a problem with old material, made with less sophisticated stabilizing agents; nonetheless, even modern hard rubber is not immune.
Red hard rubber token, dated 1861
Hard rubber was marketed under a number of different names. Ebonite and Vulcanite are two trade names for hard rubber that ended up as generic terms that remain in current use even now - even though some "ebonite" articles are no longer made with real ebonite!
Hard rubber's heyday was in the 19th century. By the early 20th century, other plastics had come to the fore. Still, hard rubber retained its primacy in certain areas, and not just for industry. Hard rubber is prized to this day as a material for pipe stems, and it is ideally suited for fountain pen feeds and sections due to its wetting properties and its ability to be heat-molded. Hard rubber has a good feel in the hand, warm and comfortable, and its absolute opacity gives it a unique look entirely different from other plastics, all of which are at least somewhat translucent.
Much of the hard rubber made today is not suitable for the making of fine objects. Because of the incorporation of substantial amounts of filler - including recycled rubber waste - it often does not machine and polish cleanly, and may be pockmarked with voids and inclusions. Other "ebonites" are made using synthetic rubber and modern plastics as a binder. These hybrid materials have a distinctly different feel from old-time hard rubber: they are markedly less dense, and do not take as high a polish. Nonetheless, high quality hard rubber is still being made, though availability has been a problem - until now.
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