I'm on a guest blogger roll. Here's something about 11th and 12th century metalworking finds from Sigtuna near Stockholm by my friendly colleague Anders Söderberg. He and our mutual friend Ny Björn Gustafsson are making sense of stuff that usually ends up with burnt daub in large anonymous sacks that nobody ever opens. Impressive work!
The excavation of the Trädgårdsmästaren block in Sigtuna 1988-90 hasn't yet been published, but the dig is of tremendous archaeological value since it covered 1100 square meters and spans about 270 years, from the founding of the town in the late 10th centiry until the mid 13th. Together with my colleague Ny Björn Gustafsson, I've had access to the finds of fired clay, slag and technical ceramics -- such as like moulds and crucibles -- from the excavation. They have turned out to contain loads of information.
The finds tell rather concrete stories about the development of metal crafts in the town, from discreet and vague production of luxury goods in the early 11th century to commercial production of larger volumes in the 12th. Also, the site probably hosted a mint under King Knut Eriksson in the 1180s. Signs of this activity were secured already during the excavations, but now it can be verified by traces from extensive precious-metal refining work in the area. Thereby we can also spot the remains of what may have been the mint's assaying office, where silver bullion was refined and tested before being struck into coins.
2) A cupel, a small vessel made from bone ash used for silver analysis, probably connected to the minting in the late 12th century. Width c. 35 mm.
In the mid-11th century a permanent jewellery workshop was set up on one of the town plots. This seems to have been an important workshop, under command of an important owner, as it appears to have housed a goldsmith from Kiev judging from the find of a crucible of Russian type. An identical crucible has been found in Kiev, connected to royal or aristocratic contexts, and so far this is the only one of this type found in Sweden. Early Sigtuna had close connections to Kiev by marriage between the royal families. Obviously at some point a delegation brought a goldsmith over, who worked in the workshop for some time.
The crucible from Sigtuna (left) compared to the almost identical crucible from Kiev (right; after Karger 1958).
A famous retinue, contemporary with the crucible, landed in Sigtuna about 1045, when Harald Hardrada stopped on his voyage from Constantinople to Norway where he was later crowned. He brought with him great wealth as well as his new wife, Princess Ellisiv of Kiev, granddaughter of Olof Eriksson, King in Sigtuna, and daughter of Grand Prince Yaroslav of Kiev. It's certainly tempting to connect the crucible to that very delegation, but speculative, as it is something we won't ever be able to prove. Despite this, the crucible is strong evidence for the connections between Sigtuna and Kiev in the 11th century.
The finds from Trädgårdsmästaren are voluminous, and by this investigation we've merely scratched the surface of the information contained in them. A long paper on our investigations, "Från prestigevarugjutning till myntning, tidigmedeltida metallurgi i Kv Trädgårdsmästaren, Sigtuna" has recently been published in Situne Dei 2007, the annual of Sigtuna Museum.
[More blog entries about archaeology, vikings, vikingperiod, Sweden, medieval, middleages, metallurgy; arkeologi, metallurgi, Sigtuna, vkingar, vikingatiden, medeltiden.]
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Now that is an odd shape of crucible. I've not seen anything like it in what I have read about stuff here in the UK. Our crucibles tended to be more "normal" in shape, round, open topped etc.
Have they worked out a way of analysing if there is any residue inside that one and if so, what it is?
Also, its more evidence for cupellation being in use all over the place even earlier than I had seen before.
Only one crucible? Doesn't sound like they had a master from Kiev - quite the opposite. Maybe they just had a sample from Kiev, and the local master was expected to make copies, but for some reason didn't.
For Guthrie: This is a specific Russian type of crucible. In Scandinavia "closed" crucibles were used in the Migration period, of a similar "integral lidded" shape like you probably know from Dinas Powys in the UK, but those completely went out of use in favour of the classic thimbleshaped crucibles during the Merovingian and Viking eras.
In Russia the tradition of using closed crucibles spans from at least the 8th century and up into the 13th. The tradition is later and thus probably independent of the Western European tradition. The shapes and structures of these eastern crucible types differs from the "Dinas Powys" style, which makes it very easy for us to decide the origin of the crucible in question.
And yes, Sigtuna is rather stuffed with cupellation residue, since a lot of silver probably was handled there in the earlier 11th century, and since the town have housed three (!) mints; in the late 10th/early 11th century, in the late 12th and the mid 13th centuries.
For Lassi: First, lets remember that the technical ceramics from Sigtuna generally are very fragmented and the fragments are scattered over the plots. Its a matter of extrem luck that this crucible, with its delicately thin walls, have survived at all. This means that we don't at all know how many crucibles of this type that actually have been in use in Sigtuna originally.
Craftsmen are generally conservative, in a way that they tend to stick very hard to the methods they've once learned. This goes for the design of tools as well. Tool design is generally extremely conservative and survives over wide spans of time. It's a lot more conservative than jewellery design - there are changes in styles from time to time but you make the new designs using the same tools you've always used.
Compare to scissors, hammers and tongs! - as well as metallurgical specialities as scorifiers and cupels - here we are talking about at least 1000 years and up to 2000 years of unchanged design.
There's no point in changing a shape that works and as a craftsman I know that I attain the best results with the type of tools I'm used to since I was an apprentice. So why change?
This means that the change from the integral lidded crucibles of the Merovingian Period in favour of the thimbleshaped, is a rather dramatic change that probably contains a lot of hidden information.
If you ask a potter in Africa why he choses traditional designs for domestic pots instead of making different and more free and innovative designs, he will just answer, probably a bit surprised, "Why do you ask? this is simply the way pots are made!". Period.
I think the same goes for 11th century craftsmen in Northern Europe. I don't think the occurence of this crucible is a matter of adaption of foreign design.
The local goldsmiths in the Sigtuna workshop used their traditional crucibles, and the guests sticked to the crucibles they were used to.
Woops - long answers! - Important questions! :)
Sorry Guthrie - I forgot your second question:
No, there are no metallurgical analysis made. But as the crucible is small and would contain just 4 to 6 cc's, I'd guess it was used for noble metals.
Although this is nothing more than an interesting side observation:
We had put together a simple living history demonstration of Viking Age small metal casting in bronze for a presentation a couple of years back at the Haffenreffer Museum of Anthropology (Brown University - Rode Island USA). We had used general sources across the Norse in general, rather than detail to one specific site and date. We had made up a number of potential designs for working crucibles, ranging from simple cylinders with side spouts to ones almost identical to the sample artifact discussed here. Although this manufacture was guided by the artifacts, there was a lot (!!) of 'intuition' based on our experience with working charcoal fires and years of modern metal casting.
close up of heating crucibles
We actually found the pinched off style crucible heated most effectively, it seemed because of the higher proportion of surface area to volume. The cylindrical open topped samples suffered from a considerable problem with ash falling in the tops as the charcoal was consumed. This however could be easily corrected by placing a flat piece of charcoal over the open top as a lid. Shifting of the charcoal bed as fuel was consumed proved more of a problem with the cylinders, threatening to spill the contents. Again the pinched off style was more resistant to this.
There was some problem judging the correct amount of force needed to firmly grip the pinched crucible lug. At least once on the test the hot ceramic crumbled away as we attempted to lift the crucible out of the fire. (Obviously practice and a standard clay type/ mix would solve that problem.)
Darrell
Supplementary details on the Eastern lidded crucible:
I've just talked to Natalia Eniosova, archaeologist from Moscow and specialist on Viking metalcraft and jewellery production. She told me that analyses of similar crucibles as the ones from Sigtuna and Kiev indicate use in silversmithing. The type is very common from Kiev in the south to Novgorod in the north.
I have made my own crucibles with regular natural clay bought at the hobby store and mixed with alot of sand. the furnace i set up uses hardwood charcoal. i have an issue with my temp not being high enough..it only achieves partial melting..how deep is your furnace? what is the size of your crucible (how much weight is melted at one time?)