A wooden barrel full of wrought iron lumps known as osmonds has been raised from a 16th century shipwreck off the Baltic coast of Sweden. The discovery of a large amount of osmond iron is rare, with only three other wrecks known, and this is the only shipwreck ever found in Sweden laden with one of its greatest exports.
On Friday, May 24, the barrel with osmotic iron was lifted out of the water for the first time in nearly 500 years, in front of a mass media gathering. The barrel, which is partially broken and where the load is visible, will now be taken care of by a conservator and further examined. Among other things, they hope to find out what the Osmunds were used for and where they were going when the ship sank.
“Now that the barrel is up, it’s very nice. It was incredibly difficult to get it out and get it off – the barrel is so heavy and [the wreck is at] a great depth,” says museum wreck marine archaeologist Jim Hansson, project manager.
The ship, dubbed the Osmond Wreck after its cargo, was discovered in 2017 by maritime archaeologists from Vrak, Museum of Wrecks, north of Dalarö in the Stockholm archipelago. The wreck was a clinker-built ship of a design characteristic of medieval construction. It was in unusually good condition for a clinker built vessel, its mainmast still standing, all the rigging intact, cargo still in place. It was clear from the first dive that most of the cargo was a rare find: barrels full of fist-sized lumps of iron. Out of the 30 visible barrels at the site, 20 of them contained osmond iron lumps averaging 300 grams each. There were also barrels of tar, ash and butter in the ship’s hold.
Dendrochronological analysis of the wreck’s timbers and the wood of the barrels date the ship’s construction to the 1540s in Stockholm. The deck was repaired around 1553 with wood felled in southern Finland. It did not sail long after the repair, so archaeologists believe it sank in the 1550s or 1560s.
Osmond iron was the first furnace-cast iron produced in Europe, and Sweden was the early center of production. It was one Sweden’s most important exports from the 14th century until 1620 when King Gustavus Adolphus prohibited the export of unfinished iron so he could turn it into field artillery and weapons for Sweden’s new and much stronger military.
Despite the immense significance of osmond iron to Sweden’s industrial and economic history, very little is known about the practicalities of the trade, the ships that were used, the maritime routes, the production process and the quality and composition of the iron itself. Vrak is working with Jernkontoret, the Swedish iron and steel producers’ association, to take full advantage of this unique opportunity to study 16th century iron.
The purpose of the new project is, among other things, to find out more about the cargo’s history: Do all osmunds come from the same place? Is it true that all osmunds should be the same size, as historical sources indicate? Through the salvage, the researchers hope to get many more clues to the early Swedish iron handling and how it worked.