Ebonite, a compound of sulfur and natural rubber, is a synthetic resin discovered by Charles Goodyear in 1839. It is difficult to process and requires advanced technology for manufacturing, but it is the best material for fountain pen barrels because of its elasticity, durability, and resistance to acidity from ink and dimensional deviations over a long period of time. Most of Nakaya’s fountain pens are protected by coating the surface of the ebonite barrel with urushi lacquer, which makes them even more durable.