To fill the urn, players must smelt bars or form cannonballs in the furnace. Smithing items from the bar does not fill the urn. The urn is filled when the player has earned 1,250 Smithing xp with the urn in inventory. Once the strong smelting urn is full, it becomes a strong smelting urn (full) and can be teleported to Ernie for 250 Smithing experience. A strong smelting urn costs coins to make if the soft clay and fire runes are bought from the Grand Exchange.