'Loki' Smelter - part 2

Early Iron 3 Symposium
October 7, 2006.

If you are wondering where the name 'Loki' comes in....

At SmeltFest in March, Dick Sargent and I build and twice fired a larger
modified version of the basic clay cobb furnace. Reaching the point in
my smelting experience where I'm less frantic over the process, I
decided to play a little with the clay - and sculpted the base of that
furnace. I shaped the jaws of a serpent or dragon, which in effect spat
out the flame at the mouth of the smelter. Vandy christen this furnace
'Jormungand' - named for the World Serpent of Norse mythology.
(If you are interested, see the report on that smelt - over on the Iron
Smelting part of the main Wareham Forge web site.)


The image above shows the smelter under construction. My standard method
has been to use a form, usually sheet metal, to create the interior
spacing of the smelter. As was done with Jormungand, the form in this
case was a length of stove pipe. I had found an ideal 8' (20 cm)
diameter piece in the barn. This was covered with a layer of paper to
keep the clay from sticking to it. (An important step!). The three half
bricks that formed the tap arch are also covered this way before the
clay work starts. Note also the shallow pit dug in front of the smelter
(which rests on the ground) to ease the tapping of slag.

The first batch of clay cobb I mixed up was a bit on the sloppy side.
Skip Williams had suggested the addition of charcoal fines to the
chopped straw and powdered clay mix that I have used in the past. He had
good results with the charcoal mix in smelts he had recently undertaken
in Holland at a European gathering of iron makers. So I altered the mix
to roughly 50 % clay, 25 % chopped straw and 25 % charcoal fines. These
all by rough volume. I have found in the past that the type and
condition of the straw actually makes a big difference in how much water
needs to be added to the mix. The straw we scrounged up from the old
barn at Peter's Valley was not ideal - either in terms of plant matter
or dryness. With the use of the charcoal addition as well, I just plain
got my proportions wrong.


The overall shape, with the slightly expanded base, was not entirely
intentional. I had built up the first lower section to about The long
and short of all that was that the first layer of clay was too damp,
and started to slump under the weight of the second lot that composed
the upper half of the smelter. This layer had started at roughly 7 - 8
cm thick - but was slowly expanding to closer to 10 cm. To stop further
slagging, I found some piece of scrap lumber and tied them in a rough
circle around the base. These pieces would remain in place through the
initial drying fire step. The end result was the rather elegant
shouldering of the bottom part of the finished smelter - just about at
tuyere level.

As with most of my recent smelts, I used a ceramic tube for the tuyere.
I have been getting these from a local potter's supply house. The
original function of these tubes are as shelf supports for porcelain
kilns. They are rated not to slump until about 1200 C - about the
operating temperature of the smelter. The tubes come 30 cm long and have
a 2.5 cm interior diameter. For those who have looked at the
archaeological evidence for early smelters in northern Europe -this 2.5
cm interior diameter is relatively consistent. The cost of each of these
tubes is about $10 delivered to my workshop. They have been used for
most of our smelts for the last year (about 10 so far) with good results.


With the tuyere tube in place - I was struck right away with the
shoulder, well, being a shoulder. The tuyere forming a mouth or tongue.
It proved fairly easy to add two eyes, projecting eye brows and a
drooping moustache. A final touch was to cut two shallow holes into the
body of the smelter to create the pupils. When the smelter was at full
heat, the result was two orange glowing eyes!
There are a number of bellows stones with simple line carvings of faces.
usually interpreted as being the god Loki. Generally the Norse had a
very arms length relationship with the divine Powers. Since Loki is the
trickster, depicting him blowing on the forge may have been an attempt
to harness his aspect in an attempt to control the fire. Any smith (much
less a smelter) knows how easily things can go wrong in forge or furnace!

more to come....