In an attempt to streamline his previous blower and furnace design, and to make it easier to replicate, Primitive Technology builds a simplified blower from sticks, rope and mud. He then tests it with three charcoal-fired pottery experiments. Some details from his notes:
The first pot was painted with iron bacteria (iron oxide being the active ingredient). When fired, the oxide melted slightly showing minimal glazing. The clay became quite hard, possibly stoneware.
The second pot was painted with wood ash and placed on a three sided clay plinth to hold the pot in the position of highest temperature in the fuel bed. The pot softened and sagged apart catastrophically. But the ash glaze gave a dark green smooth finish (difficult to see in the video).
Finally, a pot was place upside down on the grate and a cylindrical brick made of iron bacteria, charcoal powder and wood ash was put on top of this. The brick melted over the pot, covering it in a viscous blob of slag rather than a thin glaze. On inspection, the slag had 1mm sized spheres of metallic iron in it. Some of these were picked out and stored in a pot.
Primitive Technology videos often make primitive technology look smooth to execute, so it’s great to see some ‘failed’ experiments here, each potentially providing information and ideas for his future projects.Related vids: Termite clay kiln & pottery, Made by the Sea – Pottery from beach-harvested clay, Kintsugi & kintsukuroi – The art of pottery mending with gold, and traditional sword making from scratch.