My friend, crafter Aaron Richards from the Silverhand Jewelry workshop offered me a short article that revolves around the silver purity in Viking Age. I believe that the most interesting result of the work is that it shows the difference of the period silver alloy compared to the modern standardized alloy 925/1000.
My journey into the world of Viking era jewelry has been a bit of a rabbit hole. I made my first jewelry a little over 2 years ago due to wanting shiny things and not being able to buy them. I started with modern sterling silver and made a few basic bangles. I thought to myself, “Hey, I got this!” I next made some stamps to mimic that of the Viking hoards. The hoards I focused on were the Cuerdale, Spillings and Skaill Hoards. After a while I began to make money rings and hack silver items, still out of modern silver both sterling and fine. I decided to take it further by making my own custom silver blend.
One of the questions I had was where the silver was coming from. The predominant source of silver in Scandinavia was from Islamic regions. One of the primary mines was in Baghdad; this mine began to dry up in the 10th century. Once this happened the Vikings began to look to Europe for its silver (note 1). One of the sources of silver was from a mine in Lower Saxony. The Goslar mine was at the base of Mt Rammelsberg, in the Harz mountain chain in Germany (note 2).
I began digging into the Cuerdale Hoard. The hoard was discovered in Lancashire, England in 1840. It contained over 8000 items with a mix of coins, jewelry and ingots. This hoard was believed to have been buried around 905-910 based on the dates of the coins in the hoard (note 4).
I suspected the silver in the hoard could not have been the same as modern silver. In my research I found a study that used XRF (x-ray fluorescence), a non-destructive analytical technique to determine the composition of a material (note 5). In this study they tested silver ingots from nine different hoards. Ingots are lumps of material that can be used as currency or made into things. Of the nine hoards tested one was the Cuerdale Hoard. These studies show that the silver content in the Cuerdale Hoard ranged from 90.9-99.47% (note 6). There was a large diversity of purities represented in the findings. I believe there is no single source for the silver found in the hoard. The XRF results showed that some of the items tested had a very close make up to Anglo-Saxon coins, leading me to believe the coins could have been melted down to make the ingots (note 7). Another part of hoard contained a high level of silver purity, approximately 96%. This purity was inline with many Arabic coins in the hoard (note 8). A particular item I worked from in the Cuerdale hoard was ref# v1059 which was 96.1% pure. It also contained 2.1% copper, .2 % zinc, .6% gold, .9% lead and other trace elements such as tin (note 9). Another thing I found while looking into the silver of the hoard was that I believe the vikings had a working knowledge of alloying. This is supported by the fact that some of the large thistle brooches found are made with more than one purity of silver based on the part.
For example, the balls of the brooches were made of a higher purity silver thus making them easier to work and shape. The pin on this “Thistle” brooch was made of a lower purity silver with a higher copper content. The copper content would have allowed the pin to be much stronger. The increased amount of copper allows the silver to work harden, more than with fine silver (note 11). The term work harden refers to using a hammer to gently hit the metal, every hit makes it slightly harder than it was before. In my modern work I use a rawhide hammer as the rawhide is softer than the silver so it does not mark the silver. There is evidence of hammers made of antler from Birka and Jarrow. I believe these would have been used to work silver since they are hard but not harder than silver (note 12).
Antler hammers. Source: note 12.
During the Viking era the standard type of forge for a portable set up would have been a small circle surrounded by chunks of sod or stones to contain the coal for the fire (note 13). There would also be a bellows shield to protect the bellows from heat. There is an example found in Denmark. This example is called the Snaptun Stone.
There would have most likely been a pair of double bellows to increase the heat produced by the coals. Using double bellows means there is always a draft of air being blown into the coals. The use of these bellows are depicted in Carving of Sigurd and Regin, located in Hylestad Stave Church, Norway. This carving is from 12th Century CE.
A permanent set up would be very similar. The biggest difference would have been the bellows and bellows shield would have been placed on a raised platform. This was done to increase the comfort of the smith. The wood carving from the church in Norway shows it raised. Crucibles used during the Viking age were special. They were made of clay. Typically clay cannot withstand the heat of a forge. To combat this the Vikings tempered the clay with sand or ground quartz (note 17). In addition to forging tools there would have been ingot molds. These came in a variety of shapes, sizes and materials. The mold material was soapstone. An example of this can be seen from this mold found in Denmark. The silver would be added to the crucible and melted down in the coals of the forge. Once melted it would have been poured into the appropriate shaped mold to form an ingot.
Picture of a soapstone mold for casting ingots. Source: note 18.
Now that I had found the particular silver I wanted it was time to experiment and map out my blend. First thing I did was remove the gold (pricey), then decided to get rid of the lead and zinc (unhealthy) and the remaining trace elements, leaving silver and copper. Some of my future projects will explore how lead and zinc would affect the working properties of the alloy.
My alloy is around 96.2% pure, +/-.5% to allow for possible impurity in my crucible and possible oxides on the silver. I say around because I don’t personally have a way to test it. Based on math my alloy is 96.2% pure. I used 96.2grams of silver and 3.8g of copper for a total of 100g. I will be sending out a few samples to have it tested in the near future. When I first started I used the same crucible that I melted sterling silver and fine silver in, this would cause a small amount of variation. I also get my silver from a pawn shop, less expensive than buying online, and instantly available. I now use a seperate crucible for each type of silver to maintain accuracy for creating my alloy. I have also started to pickle all of my silver. This removes the contaminants from the silver before melting. Once done pickling I have a dish of clean water to remove the pickling chemical from the silver. The first step in my process of alloying is to get my silver molten, once molten I add a small amount of flux then small chunks of copper. The flux helps the molten silver to flow better for casting and gathers impurities together. I then stir it around to get the materials mixed well, I do this with a graphite rod. Then if I am making an item I pour the silver into the appropriate mold, if I am not making an item I pour into a glass jar of clean water for later use. After being poured into the water it makes small little beads that are easier to work with than large chunks of silver and much easier to weigh out.
Some working information about modern silver and my alloy
Modern sterling silver is 92.5% pure, one of my favorite things about sterling is that it gets very hard once worked making it ideal for everyday items. The con of this is if the item has to be reshaped often it must be annealed to make it soft again or risk breaking the item. Fine silver, 99.9% pure, on the other hand is a dream to work; it forms and allows for detail very easily, perfect for delicate items. Its down side is it is pretty soft over all and can become misshapen easier than sterling. My alloy 96.2% sits in the middle, hardens very nicely but remains easily workable much longer. As part of this small project I made 3 rings. One made from each type of silver. I left them unpolished to show the color. The sterling is much darker than the rest due to the higher copper content. Fine silver is very light with a whitish luster. Finally my alloy came in with a nice middle tone.
This whole process has been very rewarding. I have since converted all my jewelry to this alloy for a few reasons. One to work in silver that is closer to what the Vikings would have actually used. It also gives my jewelry something unique to set it apart from the crowd. It also works nicely for forging work. I will be diving deeper into some elements of the alloying in the future, as well as making an ingot that uses gold, lead and zinc for a personal ingot to have.
1. Graham-Campbell, James. Silver Economy in the Viking Age. Left Coast: Walnut Creek, CA. (2007)
6. Kruse & Tait. “XRF Analysis of Viking Age Silver Ingots,” Proceedings of the Society of Antiquaries of Scotland, vol 122, pg 320 (1992)
7. Kruse & Tait. “XRF Analysis of Viking Age Silver Ingots,” Proceedings of the Society of Antiquaries of Scotland, vol 122, pg 311 (1992)
8. Kruse & Tait. “XRF Analysis of Viking Age Silver Ingots,” Proceedings of the Society of Antiquaries of Scotland, vol 122, pg 312 (1992)
9. Kruse & Tait. “XRF Analysis of Viking Age Silver Ingots,” Proceedings of the Society of Antiquaries of Scotland, vol 122, pg 320 (1992)
11. Kruse & Tait. “XRF Analysis of Viking Age Silver Ingots,” Proceedings of the Society of Antiquaries of Scotland, vol 122, pg 317 (1992)
12. Bone, Antler, Ivory and Horn: The Technology of Skeletal Materials Since the Roman period by Arthur MacGregor page 172
13. Denise Heredia, Martin Hewitt, Angela Hosbein, Jenny Wang. Skallagrim’s Forge. 2016 (https://static1.squarespace.com/static/580d8074b8a79bd9bb9dac13/t/585496ee6a49635877197bda/
14. Reconstruction of Viking-age ground forge at the Cranbrook Institute of Science, 2003. Designed by Darrell Markewitz
15. Moesgård Museum, Denmark. Snaptun stone
17. Lamm, K. “Early Medieval Metalworking on Helgö in Central Sweden,” Aspects of Early Metallurgy. Oddy, W. A. (Ed.). British Museum Occasional Paper No 17. London, 1980.
19. Picture of self made gains
20. Picture of 3 rings selfmade out of each alloy