About 170 Ulfberhts have been found, dating from 800 to 1,000 A.D. A NOVA, National Geographic documentary titled “Secrets of the Viking Sword” first aired in 2012 took a look at the enigmatic sword’s metallurgic composition.
It was the sword of choice for the discerning Viking – superstrong, and almost unbeatable in battle. It was thought the technology to forge such metal was not invented for another 800 or more years, during the Industrial Revolution.
Interestingly, they are all inscribed with a single word – ‘Ulfberht’, which experts believe may reveal their maker. Yet mystery surrounds a small number of Viking swords researchers have uncovered.
It was thought that the furnaces invented during the industrial revolution were the first tools for heating iron to this extent.
Modern blacksmith Richard Furrer of Wisconsin spoke to NOVA about the difficulties of making such a sword. He spent days of continuous, painstaking work forging a similar sword. He used medieval technology, though he used it in a way never before suspected.
The tiniest flaw or mistake could have turned the sword into a piece of scrap metal. He seemed to declare his success at the end with more relief than joy. It is possible that the material and the know-how came from the Middle East.
Robert Lehmann, a chemist at the Institute for Inorganic Chemistry at the University of Hannover, studied an Ulfberht sword found in 2012 on a pile of gravel excavated from the Weser River, which flows through Lower Saxony in northwestern Germany.
This sword’s blade has a high manganese content, which signalled to Lehmann that it did not come from the East. The guard was made of iron with a high arsenic content, which suggests a European deposit.
The manufacturing process used has also baffled researchers. In the process of forging iron, the ore must be heated to 3,000 degrees Fahrenheit to liquify, allowing the blacksmith to remove the impurities, known as ‘slag’ Carbon is also mixed in to make the brittle iron stronger.
Medieval technology did not allow iron to be heated to such a high temperature, so slag was removed by pounding it out, a far less effective method. The Ulfberht, however, has almost no slag, and it has a carbon content three times that of other metals from the time.
Where does such knowledge come from in the distant past? Some big questions have not yet been answered.