The Iron of the Iron Age

How was Iron Extracted in the Iron Age?

People forged tools of the iron. Big picture © Lejre Experimental Centre

Iron is harder than bronze and is a significantly better material for tools which are used for cutting and rivets for wagons and boats. Danish iron comes in the form of bog iron.

Bog iron could be dug up in flakes and lumps and in a melting furnace is was possible to extract the iron which could then be used for making tools.

This is how blast furnaces looked. Big picture

The furnaces were made of clay and shaped like a tube which was between 1 and 1.5 metres tall and had a diameter of approximately half a metre. In the tube was placed alternating layers of charcoal and bog iron. The furnaces were shaped like a chimney, which guaranteed a strong draught. Thus, it was possible to make the charcoal to burn even stronger but they probably also made use of bellows in order to reach the necessary temperature.

The temperature in the furnaces could not get high enough (higher than 1,200 degrees celcius) for the iron to melt properly but the heat was strong enough to melt away the dirt that was stuck to the iron deposits and allow for the iron to be cleaned. It could now be hammered out to knives, axes and scythes.

However, the bog iron was not good enough to be used for long swords which meant that iron was imported from the countries south of Denmark to be used for forging the swords.

It was in particular in Jutland that iron was extracted from bog iron. The things left behind consisting of slag and parts of the melting and blast furnaces tell us the story of a massive production of iron which in some places must have required specialized artisans.