The plain smelting urn (r) is created by using a fire rune on a plain smelting urn (nr). It can be used to collect scraps while smelting bars that require level 50 Smithing or lower. Once it starts to get filled, it becomes a plain smelting urn. The Artisan's Workshop bars (ingots) will not work. It will not be able to become a smelting urn if the player owns 10 completely filled smelting urns or has another partly filled smelting urn in the bank or inventory.