EMAP_2012_Report_6_1.pdf (7.3 MB) - The Heritage Council

2.2: Iron artefacts on Irish early medieval sites
EMAP 2012 found that iron artefacts were present on 173 of the 317 settlement sites within
the EMAP gazetteer and are the most frequently found object class (Map 2.1). The durable
nature of this material meant that it was used to produce a wide range of common tools,
equipment and other objects. These typically included knives; awls; chisels; hammers;
punches; axes; saws and tongs. Agricultural tools included sickles; shears; bill-hooks; ploughsocks
and plough shares. Ornate objects of personal adornment were nearly always produced
in copper-alloy or silver though simple pins and penannular brooches could be occasionally
manufactured in iron but these were rarely lavishly decorated. Military artefacts were
manufactured in iron and included swords; spear-heads; arrow-heads; shield bosses; and the
famous slave collar from Lagore (Hencken 1950, 115–7). Other objects of iron included
tweezers; ladles; horse harnesses; buckles; keys and barrel-padlocks; bells; and the
ubiquitous iron nail (Comber 2008, 112–3). While many of these objects were functional they
also had symbolic power. For example iron knives could be deeply personal objects,
sometimes with decorated bone handles and used for a wide range of tasks and were
occasionally buried with people. Although iron objects are a very common find on early
medieval settlements, they are frequently severely corroded and without the support of X-ray
techniques, it is often very difficult to establish their precise size, shape, use as well as details
about their construction and decoration (Edwards 1990, 88).
2.2.1: Metallographic Analysis of Artefacts
The archaeometallurgical examination of early medieval iron artefacts from sites rarely takes
place in conjunction with the analysis of residues. A number of key studies have taken place
and have looked at the evidence for the hardness and durability of the objects produced.
Making steel required a high carbon alloy which required heating to a critical temperature and
then quenching in water to produce steel. Crucially this cutting edge was very sharp but
susceptible to breaking. Phosphoric iron typical of what was produced from bogs naturally
became hardened as it was worked. Rapid cooling in water did not harden the object (Jones
2009a, 255-265). Scott used chemical and metallographic techniques to examine early
medieval iron artefacts from a range of Irish sites. He found that they had significant
variations in carbon content and noted techniques such as quenching and welding (Comber
2008, 120). At Killickaweeny work by Photos-Jones demonstrated the craft of the blacksmith
in producing objects such as an iron knife and a chisel (Jones 2008b, 53-54). She concluded
that while the knife may have been imported the chisel had the ‘fingerprint’ of being made on
site. The chisel analysed was made with phosphoric iron with an even carbon content and
indicated the smith chose an appropriate bloom for manufacturing based on the objects
intended use. A knife from Johnstown was also studied. The hilt and the blade were found to
be made from two different blooms containing phosphoric iron. It was a low carbon alloy
which matched the slag samples from the site (Photos-Jones 2009, 262). A study of the
fifteen iron artefacts from Deer Park Farms found that two objects had successfully quenched
and tempered steel within a knife and an axe which had also been looked at by Scott (Hall
2011, 304-14). An awl was made from medium carbon steel. While other knives had low
carbon content they would still have provided serviceable cutting edges. The Deer Park Farms
objects could have been made by seasonal smiths with limited knowledge of carbonisation or
highly skilled smiths who deliberately made harder wearing but not fully hardened objects
(ibid. 314).
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