Iron-ing it out, nail-ing it down: A new multi-period methodology and typology for recording structural iron nails

by Katie Manby

Katie Manby explained that structural iron nails, the most common iron artefact found during excavations, were regarded as having little archaeological value. Today’s talk was to show that in some cases, iron nails could reveal interesting, previously lost, information. 

Katie gave us an introduction to wrought iron nails; how they were made by a blacksmith, and with the ‘shank’ being the part of the nail between the head and the sharp tip. Later, she would explain how shank morphology was useful in determining how a nail was once used.

We looked at previous typologies of nails, such as that of Cleere (1958) based on just 150 nails from Brading Villa, Isle of Wight. The typology of Manning (1985), who studied well-preserved nails found in London at the British Museum, was mostly used to type Roman nails, whereas the typology of Goodall (1980/2011) was used for medieval nails.

Katie talked of issues with these typologies, especially in what was recorded, such as the shape of the nail head, which was of little use in determining how the nail had been used. Manning’s Type 1b nail tended to predominate, usually representing 80-90% of all nails found on Romano-British sites, and yet it was not known how exactly they were used.

We saw examples of nails as found on archaeological sites, including un-identifiable lumps of rust, where only X-rays could reveal what lay within. Katie talked of poor storage conditions in some museums, where iron nails kept in non-airtight containers in damp rooms would eventually completely decay into rust.

A survey of current nail recording practice showed a wide variety of approaches, with some archaeologists using Manning’s typology, others using none, a few people noting details of certain nail types, and with nail count and weight usually recorded. Katie explained that from this recorded data, she had been unable to ascertain how the nails had been used, so she had turned to shank morphology.

By studying the shape of nail shanks, Katie hoped to determine how the nails had been used. We looked at a variety of nail shank shapes; straight, curved, s-shaped, turned, hooked, double clenched, and a very odd-looking nail with a curled shank. Katie also used experimental blacksmithing to further her research; making wrought iron nails, hammering them into wood, and then trying to extract them.

What Katie learnt was that wrought iron nails were soft, and needed a pilot hole in the wood to get them started.  Also, that when she attempted to extract nails, especially long ones, the heads often broke off, meaning these nails could not be re-used. 

She also found that clenched nails were impossible to extract without damaging the nail. We looked at an image of clenched nails holding two pieces of wood together, with the nails’ shanks bent over at right angles to ‘clench’ the nail to the wood. Katie pointed out that with clenched nails it was possible to measure the distance between the head and the bend in the shank; the internal clench length, and hence determine the total thickness of the two pieces of wood.

Katie then introduced the A14 Cambridge to Huntingdon Improvement Scheme excavations, where a total of 5775 nail fragments had been found, of which 1569 were Manning’s Type 1b, and 1122 were hobnails from boots. The nails were grouped by context, and we looked at those found at the River Great Ouse, Settlement 2 site.

At this site there had been organic settlement in the Iron Age, developing in the Roman period into a planned settlement fronting a villa complex. We looked at the lengths of the nails found here, ranging from 18.2 to 170.0mm, and also the internal clenched lengths. These ranged from 10.2 to 91.8mm, with a positive skew to smaller lengths of 16.2 to 33.7mm. In other words, most of the clenched nails had been holding together small pieces of wood.   

We looked at a map of Settlement 2 showing where the nails had been found. Most were located at three main areas. The first, a blacksmith’s forge, showed a higher concentration of nails than at nearby buildings. Dumped nails included many used nails, and the blacksmith did not seem to have been interested in recycling. With wooden forges more likely to burn down than other wooden buildings, it was thought that the large number of used nails found could have been the remains of previous forges.

The second area studied included a Late Roman multi-phase building and a midden. The midden contained large numbers of used nails, their condition suggesting that they had been discarded while within wood, and with no attempt made to extract and recycle the iron nails. The pattern of internal clenched lengths, which showed the thickness of the pieces of wood held together by the nails, suggested different types of construction, possibly within the same building.

The third area looked at comprised a multi-phase Roman timber gateway and a trackway. The 36 nails excavated from one deposit near the gateway may have been manufactured for a specific purpose. From the trackway came a variety of nail shank shapes including 16 straight, 6 curved, 4 turned and 2 s-shaped nails. Also found here were 2 curled shank nails, and a nail with such a large head, it was thought to be a decorative stud.

From her studies, Katie had various recommendations for the future recording of nails. These included the X-raying of all nails (if possible), more detailed recording, including the noting of clenched or otherwise modified nails, and not wasting time by recording weight!

Katie showed us her new Nail Typology and Condition Scale. Nails were grouped according to size and shape, and labelled according to their likely function, such as general use, weight-bearing, decorative, etc. Katie’s condition scale gave more detailed information than one we had seen earlier, which simply classed nail condition as ‘good’, ‘moderate’ or ‘poor’. Katie also suggested detailed recording of individual nail groups, for example, those from burials, and from formation or demolition deposits.

In conclusion, Katie emphasised the need for a consistent recording practice, and the need for a new usage focused typology. She pointed out the importance of shank morphology in determining usage, and hence the need to record shank data. Evidence to suggest straight, curved or s-shaped nails had been extracted from wood for recycling, as suggested by other archaeologists, was difficult to find, and the likelihood of any nails actually being recycled needed to be studied further.  There was a need for further experimental work, which appeared to be an enjoyable prospect for Katie!

Report by Joan Burrow-Newton