This article is based on an experimental iron furnace based on the evidence from examples identified at the archaeological sites of Benangin and Temelalo in Central Kalimantan, Indonesia. Based on experimental results, we were able to answer some important outstanding research questions regarding ancient iron processing in Kalimantan from the 14th century CE onwards. For example, we were able to demonstrate that the ancient inhabitants of Kalimantan were able to undertake all the processes of iron-working from raw material sourcing and smelting to the manufacture of tools.