Definitions for "Hard rubber"
Material used for pen barrels, caps, and other parts. Derived from natural latex resin, vulcanized (boiled with sulfur or other reagents) to form a solid, resilient, lightweight plastic-like material that can be machined into shape. Can tarnish or dull with age and exposure. Also called vulcanite or ebonite.
also known as ebonite or vulcanite; early naturally-derived plastic made by vulcanizing latex rubber with a large proportion of sulphur; the usual material for fountain pens up until the second half of the 1920, and used for decades thereafter for feeds and sections
a hard nonresilient rubber formed by vulcanizing natural rubber