A bathus bar is a bar of refined Bathus ore. Its colour is black, like Coal. It can be created through the Smithing skill by using bathus ore on a furnace, requiring level 10 Smithing and granting 13.3 Smithing Experience. The bathus ore itself can be mined from the rocks scattered throughout the dungeon, obtained as a monster drop, or bought from the Smuggler.
A bathus bar can be smithed on an Anvil through the Smithing skill to create Bathus equipment, granting between 19 and 23.5 Smithing experience per bar used. A list of bathus items that can be smithed from bathus bars and the Smithing levels required can be found here.
Five bathus bars are used along with 5 seeping elm branches to build a farming patch in the hotspot located in the start room of a dungeon.