THE CRAFT OF FIRE

We tried to enter the Bronze Age but can't seem to leave Aluminum! Last weekend, we fired up the bronze furnace.  We made a hole for the pyrometer about 18 cm from the bottom, brought it out to the backyard, and got a little fire going within it. We lay ceramic fibre down under the furnace too, to further insulate it below (the clay floor is a bit thin).  Then we placed our crucible inside, on a bed of charcoal. It's loaded up with scrap pieces of brass that I had: a door handle, strike plates, some fittings, etc. There was no lid; the charcoal covers it and prevents oxidation. We added store-bought BBQ charcoal and then more or less sat back and watched it go.  We topped it up a couple of times and sometimes we'd blow some air (lung-powered) into the bottom to get the new charcoal to catch more quickly. The furnace held up very, very well. A few, thin cracks appeared when we were up quite high in temperature, around 700-800º C.  The highest temperature recorded was ...

Here she be: the primitive bronze furnace! It's not quite the same dimensions as detailed in the Asmus article which we were following, basically because we ran out of clay. It's about 34 cm high, 45 cm wide at the bottom and 28 cm at the top, with an opening of 16 cm. There are three openings below which are 10 x 6 cm, as per Asmus ' design. It took two sessions to build it, but really only about 4 hours of total work time, once we had nearly all the crushed up grog to work with, and the rehydrated clay .  In between the sessions, it was very important to keep what we had built moist so that we could add fresh clay to it next time. So we wrapped up the half-built furnace in many damp rags, and also covered it in plastic.  And I wrote myself a little note with a phrase I have never written or uttered before: Every few days I would go in to the garage and "water the furnace", moistening the rags to keep the clay soft.  The Principle that we were studying that mon...