Ebonite

:"This article details a type of plastic, for the manufacturer of bowling balls, see Ebonite International"

Ebonite is one of the earliest forms of plastic. A hard, rigid and shiny resin, it was intended as an artificial substitute for ebony wood. It is actually a very hard rubber first obtained by Charles Goodyear by vulcanizing rubber for prolonged periods. As a result, it is about 30% to 40% sulfur.

Applications

It is often used in bowling balls, smoking pipe mouthpieces, fountain pen nib feeds, and high-quality saxophone and clarinet mouthpieces. It is also commonly used in physics classrooms to demonstrate static electricity.

Hard rubber ('Ebonite' is a brand name that's not universally used) was used in the cases of automobile batteries for years, thus establishing black as their traditional color even long after stronger modern plastics were substituted. It is used in hair combs made by Ace, which survive, essentially unchanged, from the days of the US Civil War.

Properties

The material is brittle, which produces problems in its use in battery cases for example, where the integrity of the case is vital to prevent leakage of sulphuric acid. It has now been generally replaced by carbon black-filled polypropylene.