Ebonite

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

Ebonite is a very hard rubber first obtained by Charles Goodyear by vulcanizing rubber for prolonged periods. It is about 30% to 40% sulfur. Its name comes from its intended use as an artificial substitute for ebony wood. Ebonite is a brand name — it is also known as vulcanite or hard rubber.

Applications

It is often used in bowling balls, electric plugs, smoking pipe mouthpieces, fountain pen bodies and nib feeds, and saxophone and clarinet mouthpieces. Hard rubber is also often seen as the wheel material in casters. It is also commonly used in physics classrooms to demonstrate static electricity. It was used as an insulating material in early electrical and electronic apparatus before bakelite.

Hard rubber 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, part of Newell Rubbermaid, 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 sulfuric acid. It has now been generally replaced by carbon black-filled polypropylene.

Contamination

Ebonite contamination was a big problem when it was used for electronics. The ebonite was rolled between metal foil sheets, which were peeled off, leaving traces of metal behind. For electronic use the surface was grounded to remove metal particles.

ar:إبونيت