Polynesian objects from early European exploration, £19.99
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Investigating a dagger sheath through conservation
Modern scientific techniques like X-radiography allow more to be learned from ancient artefacts than was previously possible. Many of us have had X-rays taken of our chests, broken bones or teeth. X-radiography is a common but valuable tool for the doctor or dentist, and for the conservator too.
Most archaeological metalwork is heavily encrusted with corrosion when it is found. This can be quite bulky, hiding the true size and shape of the object. Sometimes it might not even be clear what the object is. Any decoration is hidden as well, as it was on this iron plate from a Roman dagger sheath. All ancient metals except gold can corrode in this way, but iron is particularly susceptible. The corrosion can expand into a mass of thick rust, with laminations, pits and pustules. The artefact can never regain its original form, but X-rays can tell us what that form was.
The dagger sheath, from Hod Hill in Dorset, was heavily corroded. We could see what it was, but in order to know more, it was X-rayed. Twelve rivet-holes for securing it to a belt were revealed. The X-rays also showed decoration in a geometric pattern: well worth the lengthy and painstaking work of removing the overlying corrosion. Using hand-tools under a microscope investigative cleaning revealed the decoration as an inlay of brass metal strips. Some of the 'petals' on the rosettes also had remnants of yellow enamel inlay. The design would have stood out brightly in colours of gold and yellow, on a silvery or dark background.