Ebonite

Ebonite, also known as hard rubber or vulcanite, is a hard, dense form of vulcanized rubber that is typically black or dark brown. It is produced by vulcanizing natural rubber with sulfur at elevated temperatures, creating a cross-linked polymer network that renders the material rigid and resistant to deformation.

Compared with untreated rubber, ebonite is less elastic but exhibits high abrasion resistance, dimensional stability, and electrical insulation. It also shows good resistance to many oils and solvents, though it can become brittle at low temperatures.

Historically, ebonite was widely used for electrical insulation components and other hard-wearing parts in electronics and everyday objects, including knobs, handles, and fittings. With the rise of plastics such as Bakelite, its use declined, but ebonite remains valued in specialized applications where high dielectric strength and chemical resistance are required.

Today, ebonite is manufactured for niche components and archival items, and it is appreciated by collectors for antique scientific instruments and traditional fountain pen parts. While largely supplanted by modern polymers in most consumer products, it endures in areas that benefit from its distinctive combination of rigidity, durability, and insulation properties.