Note : This commentary was written in 2016, intended to be my
contribution to the then planned booklet describing the Turf to
Tools project, which would have included a number of other
authors. Readers will find much of this material incorporated into
the finished paper from 2023.
Turf to Tools
A View from an Artisan Maker
Darrell Markewitz
Turf to Tools was initially conceived as "... an ongoing
investigation in to landscape, material and craft, inspired by local
archeological investigations in Rhynie, Aberdeenshire."
I come from a camp that lays between the pure conceptual Artist and
the Technician. As I understand these terms at SSW, the Artist being
defined as one most concerned with developing ideas. The Technician
being more concentrated on physical methods. As an Artisan Maker, my
own work is often bounded by functional considerations, but I strive
to design an object still pleasing to look at. There may be an
element of the thought provoking as well, but most commonly this
remains secondary to the demands of function and the desires of
form.
As an individual, I find myself a bridge between a number of quite
different fields. I have a long working experience in the very
technical realm of the blacksmith / metalworker. Along with having
come from an formal education in art school. Being known as
knowledgeable in early North European, especially Viking Age,
material culture - and the public presentation of the same. In
recent years becoming more and more involved in experimental
archaeology (itself a span between the academic researcher and the
practical field worker).
Each 'camp' has its own method of both approaching subjects, and
often distinctive (even conflicting!) descriptive language. Added to
this ball of string is the fact that there are international
differences, including (certainly at the Scottish Sculpture
Workshop) multiple language users.
Given I'm from Canada, with a large body of work ranging over many
types, and with 'many irons in the fire', what can I say about the
Turf to Tools project?
My involvement with Turf to Tools came in through the side door.
Eden Jolly had initiated what I would call a 'proof of concept' for
the over reaching frame of the project : utilizing local raw
materials, through regional historic based methods, to create
functional objects. His background research into this all lead him
to my own internet available documentation. A personal conversation
started via e-mail, helping him with his first attempt at a bloomery
iron smelt. Someplace along this line, Nuno Sacramento had contacted
me to see if I would be interested in coming to SSW and directly
participating in the project. In this case, those 'many irons'
appeared to provide an ideal mix of historical knowledge, technical
skill, practical experience, and (perhaps) artistic vision needed.
The first phase in 2014 most certainly was shaped by the archaeology
of nearby Rhynie, for which the inclusion of Dr. Gordon Noble on the
project would prove of importance. So to start, T2T was framed to a
'Pictish' cultural set : North Eastern Scotland, post Roman to pre -
Viking (so 400 - 800 AD). It is a period where the minor chiefdoms
are expanding to small kingdoms, and Rhynie appears to be the site
of one of those political centres. Historically this period presents
some major problems, as this is a material culture not well
represented by artifact in archaeology. Importantly at that point
Christianity is becoming the major religion. (This significant
because one change with Christian conversion is the end of a more
ancient practice of burial with a person's life goods, thus now
limiting objects into the artifact record, especially those of daily
life.)
Evidence of ancient iron smelting technology is almost always
fractured, and honestly not well understood. Looking for
specifically first Scottish, then narrowed to Pictish period samples
at first seemed unlikely. Fortunately, it proved possible to find
some descriptions of an excavation of a small scale historic iron
production site at Culduthel, just outside Inverness. Both the close
location, and the rough dating from 200 to 400 AD, is almost good as
it could be within the random nature of archaeological discoveries.
Past work in the realm of experimental archaeology would prove
critical here, allowing for a fuller understanding of exactly how
available iron ore was transformed into workable iron bars.
The enigmatic figure found in 1978 carved in a large stone slab, the
Rhynie Man, would channel the 'object' part of the undertaking. The
cartoon like figure, likely created some time about 400 - 600 AD,
holds over his shoulder an axe. Who is depicted? What is and Why is
that axe shown? What is the original reason for the exaggerated
details : pointed teeth, big hooked nose, hair or head-dress? To
make this all more difficult, no artifact axes have been found in
Scotland for the period of reference. Within all of Great Britain,
only a mere handful have been found. Searching for a possible
artifact prototype would prove not only difficult, but
interpretations of that sample became a point of discussion within
the project.
Checking the air system, T2T smelt 1.2, 2014
(image by Kelly Probyn-Smith)
The basic equipment design employed is what I call a 'short shaft'
type of direct reduction iron smelting furnace. This consists of a
cylindrical or slightly tapered clay cobb body, about 60 to 70 cm
tall and roughly 25 cm interior diameter. The walls are hand built
up from a mix of 1/3 course sand, 1/3 clay and 1/3 shredded dry
horse manure. The manure addition reinforces, gives steam on drying
some place to expand and burns away on the interior to create a
primitive refractory material. A tuyere pipe is inserted about 15 -
20 cm above the base level, standing 5 cm or so proud of the
interior wall. The ideal angle for this is about 20 degrees
downwards, and this serves to deliver the air blast into the
interior.
Hardwood charcoal is the normal fuel (almost universally), and needs
to be of a certain size. Ore as well needs to crushed to an ideal
size, which varies depending on type of ore. There is a dance
between ore type, charcoal, clay used and the final ideal size and
layout of the furnace, and the amount of air, both volume and
pressure. Change too much of one, and all the other elements need to
be modified. (This is primarily why historic furnaces vary so much
for different physical locations.) Past experience has shown for
this type of furnace, the ideal rate of burning is 2 kg of charcoal
(about 8 litres) every 8 - 10 minutes, a process that continues for
many hours.
Ore is mixed evenly through the charcoal as it is added to the top
of the furnace. Iron oxide ore meets hot carbon monoxide gas
from the burning charcoal. This wants to be carbon dioxide,
so the oxygen is reduced from the ore, leaving fine metallic iron
particles behind. With an interior at about their welding
temperature, the particles stick together (sinter) like dark brown
sugar does. This material falls to the bottom of the furnace. Also
falling to the bottom is a rough glass formed from sand (silica) in
the ore, melted clay walls and ash from the charcoal. This also
falls, hits the cold bottom of the furnace and freezes, but remains
liquid on the top, nearest the air blast of the tuyere. Iron falls
into this slag bowl, sinking through the hot liquid glass and
stopping on the more solid bottom. (Think of a chocolate covered
cherry, the chocolate the slag bowl, the cherry the iron bloom, the
liquid slag the sugar syrup.) At the end of the smelt, the base of
the furnace is opened to expose and crack apart the slag bowl, then
grab the metallic bloom that (hopefully) has been produced.
And yes - an amazing number of things can go wrong in all this!
As with any complex project, mere mechanical problems often
interrupted the chain of exploration.
Building the initial iron smelting furnace was fairly straight
forward, overall based on Culduthel, but including those elements
found through experience most likely to ensure effective results.
What I call a 'short shaft', in this case mounted on a plinth made
of stones and This base design was pre-tested at my home workshop in
Canada months in advance. Application of a construction suggestion
by George Beasley, based on his (extensive) experience with cast
iron furnace operations was quite helpful.
The first test included use of a unique local iron ore called
Macaulayite, which proved not to be an effective raw resource. (Note
that the better part of two days effort and the expenditure of some
60 plus kg of prepared charcoal were expended!) The end result here
was a small iron bloom at 2.3 kg, an ore to metal yield of only 7.5
%.
This second firing using primarily industrial taconite ore should
have produced significantly better results, but in the end the bloom
was only 2.9 kg, a 11.5 % yield. Although jokes were made about
Scottish weather, the more likely reason was the air supply system,
via a small electric leaf blower.
The third test required the building of a second furnace. This
because the first furnace had been constructed on a wooden pallet
(topped with concrete paving slabs) to allow it to be shifted around
the work area. As it happened, moving a clay smelting furnace proved
not such a great idea, and resulted in extensively damaging the
structure. Input from artist Deirdre O'Mahony lead to a question
about utilizing peat as a fuel source. As the new furnace needed to
be baked dry, a test using suitably broken up modern commercial peat
pellets as fuel was undertaken. Although only a short burn,
thermocouple readings made suggested temperatures into the correct
operating range might prove possible (1140 - 1250 C recorded).
The third test would utilize a proven ore type, an analog developed
specifically to mimic naturally found primary bog iron ore. The
furnace design was essentially the same as before. The most major
change was the use of a stronger blower, ensuring better delivered
pressure to better force air into the furnace. In addition to the
primary iron making activity, Emma Harrison would contribute both
her effort but an additional experimental process at the close of
the smelt. For her own research project, a total of 4 kg of raw bone
was added in an attempt to create a high calcium layer to the top of
the bloom mass. Taken together, the skill of the team and the use of
proven elements showed in the excellent results. This time an
extremely dense 11.6 kg bloom was produced, a yield of 29%. This
bloom later proved so massive that staff at the University of
Aberdeen were unable (with modern tools!) to effectively section it.
Along side all this effort was the 'bloom to object' part of the
project. This was directly related to Rhynie Man, specifically that
axe. I had made a prototype back in my Ontario workshop, conforming
to earlier research I had undertaken to Viking Age tool axes. To my
eye, the Rhynie Man's axe was a well known early 800's fine tool axe
type, quite common in Norway. These slender blades, mounted to a 60
cm or so handle (as seen with Rhynie Man's) are designed to take a
fine sliced shaving off a wooden beam, for either house or ship
construction. Of course, any tool balanced for fine cuts to wood
will also make a deadly weapon. In my opinion, the Rhynie Man Axe
was an accurate depiction of a somewhat expensive, but purely
functional, tool / weapon.
Axe Prototypes made in T2T, Rhynie on left,
Sutton Hoo on right
As mentioned, there are no artifact axes that have been found in
Scotland from the Pictish period, and very few found in England
either. One of the few well known is the 'axe hammer' from the
Sutton Hoo ship burial in East Anglia. This is clearly a Saxon
culture, has many pagan elements, but is roughly contemporary at 624
AD.
As part of T2T, I hand forged a rough replica of that object for
direct comparison with the Rhynie axe. With the Sutton Hoo axe in
hand, again a likely use suggests itself. Even with the lighter axe
head and the heavier shaped iron handle, Sutton Hoo certainly feels
like a weapon intended for use on horse back. All though it is most
likely we can never know for sure, but the creation of accurate
replicas brings ancient objects to life.
As a further extension into exploring the world of Rhynie Man, Kelly
Probyn-Smith undertook working towards making a replica of the axe
headed pin that had just been uncovered at the excavations. This
small straight pin was a type most commonly used to secure a cloak
at neck or shoulder (depending on the sex of the user). The upper
terminal flared to an axe shape on one side, the other side being
drawn out then formed to a spiral coil. This appeared on the
radiograph reference images to end in serpent's head. Forging such a
small object presents its own set of difficulties. Curiously the
small set of 'jeweller's' sized tongs also recovered in the 2014
excavations at Rhynie would be the perfect tool for such delicate
work.
After all this historic and technically focused exploration, I was
certainly very keen to also create a physical object with a more
modern context. I selected half of the first bloom created, and
forged out a small bowl. Bloom iron is different than modern metals,
in terms of alloy content, physical structure and importantly,
working character under the blacksmith's hammer. As an artist, I
continue to be very interested in working with these differences,
and how in these in combination mark a finished object.
The second phase in September of 2016, would continue exploring both
the initial concepts, and new aspects based on the discoveries from
phase one. Three more iron smelts would be undertaken again using
the same basic furnace design.
A field trip in 2014 was to the nearby Lecht Mine, part of
investigating the land and local resources. This open cutting along
the edge of a small rift in the hills was operated in two phases
historically. In the early 1800's, manganese ore was extracted
there, causing the building of a stone structure with a small water
powered crushing mill (the shell of which still remains). Earlier in
the mid 1700's, iron ore was extracted. I had stumbled over
(literally!) a thin vertical vein of what looked like it might be
usable geothite ore. At the start of the 2016 phase, we returned and
gathered four pails of this ore, quality varying by the individuals
gathering. The ore gathered at Lecht was roasted, sorted and
crushed.
A new furnace was constructed, very similar in size and layout to
the ones used in Phase 1. One difference for the first smelt was the
use of a copper tube as the tuyere. This was forged into a thick
walled taper, about 1.5 cm interior diameter on the insert end, and
40 cm long.The operation of the smelter was fairly standard, save
that considerably more iron rich slag was created than normally
seen. This required four major slag taping interventions to drain
the excess lest it 'drown' the air flow at the tuyere. In the end a
large block of yellow hot slag bowl was extracted, but with
hammering only a small amount of iron was found. Total production
3.5 kg, yield at 8%. This indicates the ore gathered (remaining?) at
Lecht, although able to create iron, is too low in usable iron
content to balance the considerable effort and expenditure of other
resources to effectively extract it.
Smelt two was a full scale test of peat as a potential fuel.
Commercially harvested and compressed pellet peat, sold as home heat
fuel, was purchased. Without specific experience, the peat was
broken to pieces similar to those proven effective with hardwood
charcoal. Again the addition and measured consumption was against
pails of 2 kg. The ore used was a red iron oxide analog mix. One
other modification was the addition of 3 kg of crushed high iron
content slag for the initial charges. Although the peat fuel
certainly appeared to be consumed faster than with charcoal,
temperatures measured by thermocouple indicated lower than normal
internal temperatures. At the end of the smelt, this was born out by
the results, with only 1.5 kg of fragmented iron being recovered,
yield at just over 4 %. A large quantity of foil like metallic
gromps were also collected. Both suggest iron was being reduced, but
temperatures were not quite hot enough to effectively sinter this
together into a solid bloom mass.
Although this was intended to be the end of the smelting events at
T2T2, Eden and Uist Corrigan decided to undertake an additional test
(while they had me around to observe and assist as needed). Enough
charcoal and taconite, both proven components, remained on hand. The
furnace that was initially constructed proved extremely durable,
needing only minor repairs around the extraction arch each time. For
this last smelt, a short piece of high temperature ceramic kiln
support tube replaced the copper for tuyere, into the same position.
Once again 3 kg of iron slag was added as the first charges. (The
logic here is to more quickly form the required bottom slag bowl.)
After all the available taconite ore was added, a further amount of
mixed Lecht ore and metallic gromps from smelt 2B were also
included. Another change was the addition of a small slag port to
the bottom of the furnace, making possible a continuous tapping
process. The end result was excellent, with an extremely large and
compact bloom at 9 kg, yield at 26 %. This certainly proved the
effectiveness of the furnace operation - and the skill of the
working team.
Although the intent of phase two was to devote several working days
to the second stage process, bloom to bar, followed by the third
stage, bar to object, this in the end did not prove possible.
Although work had begun earlier on a new 'professional' level
blacksmith forge for SSW, this equipment suffered some teething
problems in getting it working correctly. Work was also massively
impacted by what proved a serious problem in securing effective coal
fuel. After several quite unsatisfactory tests, and considerable
outside consultation, it was found that the 'best' (if not only)
available coal was in fact imported from Poland. This itself was a
major surprise, and certainly reflects directly back the the framing
concept of human impact on natural resources.
One conceptual project that arose during the 2016 session was one
suggested by an even older cultural practice relating to iron
objects and landscape. In the more distant Celtic Iron Age, ornate
and expensive objects (particularly jewellery and weapons), where
often returned to the bog as sacrifices. Weapons used were often
bent beyond use - symbolically 'killed' - before being deposited.
Everyone on the Turf to Tools team thought the ideal of making a
finished object from our precious bloom iron, then returning it to
the bog from which the starting ore sprang, would make a powerful
last stage to the overall project.
Posing as Rhynie Man at SSW, 2014 (image by David Porter)
