At the beginning of the industrial age, writing instruments made of hard rubber, also called ebonite, were manufactured. This was just polished. Although brass was already used for writing instruments, but more for trim parts, such as clips and decorative rings. Only the cartridge technology enabled the use of metal on the body, since the ink had no contact with this. The brass of the Kaweco BRASS Sport develops a natural, individual patina by the user. Due to the high weight of the model, the writing instrument already presses on the paper by itself. This allows longer writing.