When the Staffordshire Hoard was discovered in 2009 (CA 236), the exquisite artistry of its contents immediately captured the public imagination, vividly demonstrating the creative powers of Anglo-Saxon goldsmiths. Now, however, a pioneering research project (undertaken at the British Museum and funded by English Heritage) has revealed that their techniques were more sophisticated still. New analysis, examining the gold content of over 100 pieces from the hoard, as well as other Anglo-Saxon objects, has revealed that Early Medieval craftsmen were using complicated chemical techniques to enrich the outer surface of golden objects, transforming their appearance to that of items made from much purer metal.
Most of the objects that we call ‘gold’, whether ancient or modern, are in fact made using alloys containing copper and silver (for example, 18- carat gold is 75% gold and 25% other metals). The gold worked by Anglo-Saxon smiths was no different, and as part of the ongoing programme of research and conservation being carried out on the Staffordshire Hoard, metals expert Dr Eleanor Blakelock carried out a pilot study on 16 objects to examine their composition.
After using a Scanning Electron Microscope to analyse the surface of each object, pinprick-sized areas of the surface were then scraped away to reveal the core. When comparing these results, she noticed a marked difference: the gold on the surfaces of the objects was much purer, with much less copper and silver present.
These surprising findings prompted a wider project, involving another 98 hoard objects, as well as 36 Anglo-Saxon items from the British Museum, and one from the Potteries Museum and Art Gallery in the largest study of its kind ever undertaken on Anglo-Saxon gold. In many, the same pattern appeared. Why?
When buried, copper tends to leach out of alloys naturally, affected by surrounding soil conditions, but silver does not. For such a disparity in an object’s silver content to exist – in some cases the pieces have a core composition of 25%-50% silver, but only 6%-10% silver on the surface – Eleanor argues that this suggests the silver was being deliberately removed from the outer surface in order to make the objects look more golden.
Closely guarded secret?
Such an intricate process may have been a closely guarded secret among Anglo-Saxon goldsmiths – certainly no description of how it was achieved has survived from the period – and for now its details remain obscure. Eleanor suggests that the technique may have been similar to cementation, a process sometimes used in modern metallurgy, wherein a salt bath of iron-rich minerals (for example, Roman tile dust) is heated, producing acid. This causes the silver in any gold alloy placed into the bath to separate and rise to the surface. Metal treated in this way initially looks dark and pitted, but it burnishes to a beautiful golden hue.
‘We don’t know if the people commissioning these items would have known that their surfaces were being treated, but it is certainly a deliberate act by the craftsmen,’ Eleanor said.
Many of the most famous objects from the Staffordshire Hoard seem to have been enhanced in this manner, including the front of the folded cross, as well as many of the filigree-decorated sword pommels, and gold surrounding cloisonné garnet work, such as on the ‘sword pyramids’ and the set of fittings for a single-edged seax blade.
All that glitters…
Does this suggest that crafty goldsmiths were manipulating the surface of their creations in order to cheat their patrons by passing off lower-quality material as pure gold? Not necessarily: in some cases the silver content seems to have been reduced for artistic reasons, particularly on objects decorated with filigree, such as the sword pommels and the pectoral cross. Here their backing sheets have been enhanced, but the delicate patterns of gold wires soldered onto them have not, creating a striking colour contrast.
These findings also have important implications for how Anglo-Saxon objects are dated, as previously an artefact’s surface gold content was often used to help establish its age. This is because a lot of Anglo-Saxon gold is thought to have its origins in recycled Continental coins, which became much less readily available in Britain after the 630s-640s, when incursions by the Islamic Caliphate into the Levant wreaked havoc on the economy of the Byzantine Empire. If, as this study suggests, surface composition is not an accurate indication of an object’s actual gold content, whole swathes of material may need to be revisited.
As the make-up of the Staffordshire Hoard is mostly martial in character, with a small number of religious items, the team turned to other collections to broaden their scope by including jewellery and dress items, including the Sutton Hoo buckle and shoulder clasps, the Desborough necklace, and finds from Taplow and Market Rasen.
This revealed an unexpected difference between personal ornaments recovered from graves identified as ‘male’, and those from ‘female’ burials: many of the former had been made from purer gold to begin with, while the latter used alloys with a higher silver content, which was then enriched to appear more golden.
Before we leap to assume that women were being palmed off with inferior goods, the team stress that this pattern is only borne out in dress items: the enhanced sword fittings of the Staffordshire Hoard are undoubtedly ‘masculine’ in character, but show a similar core silver content to the ‘female’ ornaments.
‘For all we know, it was the colour of the gold that was the priority, not its purity,’ Eleanor said. ‘There may also have been practical considerations at work: the Sutton Hoo buckle is made from very pure gold, perhaps as much as 85%-90% gold content, but it is extremely heavy. Perhaps women wanted their jewellery to be as beautiful, but lighter.’
Alternatively, the study’s choice of male dress items from very high-status graves like Sutton Hoo could have caused the disparity, added Chris Fern, an independent archaeologist who has been working to reunite matching hoard fragments (CA 290).
The Staffordshire Hoard must have been a dream exhibit for Birmingham, which has a flourishing jewellery quarter. In the museum’s new displays, these skills have been employed to full effect to create stunning replicas of a number of the most famous items – some, like the breathtaking reconstruction of the folded cross, depicted in all its unfurled glory with garnets re-attached, have been used to show how damaged objects might have originally looked; others were created for handling. The pectoral cross has been recreated for this latter purpose, its weight matched to that of the original to within a few grams – but like some of the real hoard items, its glittering exterior belies a less glamorous core: in this case, rather than gold, it is made of gilded bronze.
Splendid new display
These findings were announced this October at Birmingham Museum and Art Gallery’s launch of their new Staffordshire Hoard permanent displays (funded by the Heritage Lottery Fund and Garfield Weston). Previously housed in a small room where only a small number of key pieces could be shown, now about 70% of the 4,000 hoard fragments have been spread across long tables that explain how the unique collection is being conserved, and explore the latest findings. As this story is still developing, the displays are designed to be flexible, allowing pieces to be moved in and out as required by researchers, and for information to evolve as new developments emerge. ‘People will be learning about the hoard with us,’ said Conservation Co-ordinator Pieta Greaves.
This aspirational attitude is seen throughout the gallery: at one end of the ‘research table’, boxes of unidentified fragments form a pyramid that the team hope will gradually shrink as bits are matched and rejoined. Pieces of an ornate helmet have also been mounted on a Perspex head in an optimistically large box – with work on the hoard’s decorated silver foils planned to start in the New Year, the team hope to identify more fragments soon.
Meanwhile, other areas explore the hoard’s international story: the likely origin of its raw materials, and the cultural influences visible within its artwork. Elsewhere, a reconstructed meadhall – a structure that lay at the heart of the elite warrior culture reflected in the hoard – brings matters closer to home, introducing Anglo-Saxon England (and a crash-course in the Old English language). Star objects form the culmination of the displays, in an enclosed area dubbed ‘the Treasury’. With artefacts spotlit in this shadowy space, and a deep red lining, the showcase creates the feel of being inside a jewellery box.
From its outset, work on the hoard has been a collaborative effort, something that the new gallery is keen to reflect – there is no single curatorial voice here. Rather, video screens introduce the thoughts and theories of a host of ‘talking heads’, from archaeologists and conservators to the hoard’s finder, Terry Herbert, and visitors to previous exhibitions on the finds. Above all, the space is filled with the excitement of an ongoing process of discovery, where, as we have seen from the latest tranche of research, the new questions arising from the research are in many ways just as important as the answers being revealed.
ALL IMAGES: Birmingham Museums Trust