-Viking Age Iron-
Built for various inquiries.
Page 1 |
Page 2 |
Page 3
This is the rock base around which the smelter itself will be
constructed. So far I have found a great vein of local clay and tried
a few experiments to get the refractory qualities satisfactory. I have
thus far tried mixing wood ash with the clay and forming a crucible,
which was then fired to about 1200 F, which would approximate the
interior temp that the smelter might be taken to during the initial
firing phase. The wood ash / clay bisqued quite well though upon
heating with a torch it cracked. I am hoping to obtain a relatively
permanent material for the smelter, so the crack is a small concern. I
suspect that the uneven heating of the torch may have been a factor
which may or may not occur when the smelter is fired. I will be
obtaining some horse dung to mix with the clay according to Theophilus
and experimenting with that before finally packing the refractory
around the stone base.
Here are some of the crucible test pieces I made with the local clay.
It seems to fire well; the one on the left is unfired clay mixed with
horse dung. In the middle is a fired piece from the same mixture. The
cracked piece is mixed with wood ash, which was another suggestion that
came from some of the Neo-Tribal smiths. I have thus far only come
across historical sources mentioning dung as an addition to clay,
though I do suspect that if ash works too, it must certainly have been
used. At any rate, the ash piece cracked when I was heating it with a
torch. I am guessing that the fibrous nature of the horse dung mixture
might help prevent such cracking. The horse-dung piece was fired to
the temperature of 1600 F, which I suspect will be the middle range of
the temperature the smelter might see in use. I would fire some to the
mid 2000 F range which will be the interior temperature of the smelter
in use, but my electric kiln won't go that high. I suppose that will
simply have to wait until such time as I fire up the smelter...
Click
here to see inside. That's the tuyere on top; the tapping arch is
on the right.
I spent the better part of the day mixing the clay with the horse dung
& lining the smelter. It has taken quite a bit of material to fill all
the gaps in the rock. I will be aiming for something near a 12"
diameter with a 3 foot interior height, with the tuyere roughly 1/3
from the bottom... right now the smelter is about 1.5 feet deep. I
will probably line the completed smelter with 'lute," which is a
mixture of charcoal dust & clay. According to the U. of Bradford site this
reduces cracking of the clay during firing. As previously mentioned,
the addition of horse dung to the clay seems to perform a similar
function. Assuming the smelter works, I'd like to get as many firings
out of it as I can...
The smelter is finished & drying now. I used 3 large wheelbarrows of
clay and 15 gallons of horsedung. There are supporting sticks inside
the top of the smelter. It is approximately 11" x 27" interior. The
tuyere is 10" from the bottom. While it dries over the next week or
two I shall hopefully make some charcoal & a bellows...
This is the first firing of the smelter, to cure the refractory and to
roast some banded iron formation ore that I have. Roasting helps make ore more friable and
porous. It is kept at a temperature of 800-900 C (1475-1650 F) for a period of 4-6
hours. The furnace had no problem staying in this range so long as it
was fed a steady diet of softwood.
Roasted Ore!
