The raw material for this was blister steel, made by the cementation process.

They were leading participants in the cartel in oregrounds iron, the raw material for blister steel.

During this time, carbon diffused into the iron, producing a product called cement steel or blister steel.

The resulting crucible steel, usually cast in ingots, was more homogeneous than blister steel.

This produced blister steel.

The iron had "gained" a little over 1% in mass from the carbon in the charcoal, and had become heterogeneous bars of blister steel.

This would decrease its usefulness in making blister steel (cementation), where the speed and amount of carbon absorption is the overriding consideration.

Blister steel (made as above) was melted in a crucible or in a furnace, and cast (usually) into ingots.

In the 1740s, Benjamin Huntsman found a means of melting blister steel, made by the cementation process, in crucibles.

This made it the best material for conversion to blister steel, the main variety of steel made in Great Britain between the 1610s and the 1850s.

The successful process was crucible steelwhich was made by melting wrought iron and blister steel in a crucible.

Whilst in Handsworth, he developed the process whereby it became possible to melt down raw or "blister steel" and produce cast ingots of steel.

Eventually, after many experiments, Huntsman was able to make satisfactory cast steel, in clay pots or crucibles holding about 34 pounds of blistered steel each.

Österby's brand mark was OO, which meant that its products were highly valued in England for the production of blister steel by the cementation process.

In making crucible steel the blister steel bars were broken into pieces and melted in small crucibles each containing 20 kg or so.

Finest puukkos have blades of Damascus steel, and forging a blade using blister steel was considered the hallmark of a master smith.

Although Europeans had been making steel for nearly three centuries, the processes for creating blister steel and crucible steel were slow and extremely expensive.

When the pots are at a white heat they are charged with blister steel broken into lumps of about kg, and a flux to help remove impurities.

At that period, if steel was needed, particularly pure varieties of iron were heated with charcoal in a cementation furnace to produce blister steel (with about 1-2% carbon).

In 1740, Benjamin Huntsman began melting blister steel in a crucible to even out the carbon content, creating the first process for the mass production of tool steel.

The museum demonstrates the process making blister steel from iron and coke, then refining this steel using techniques that originated with Benjamin Huntsman's invention of the crucible steel process.

It was classified as first oregrounds and at the height of its power most of the products were exported to England, where it was converted to blister steel by the cementation process.

By 1860 there were 250 cementation furnaces in Sheffield capable of producing 80,000 tons of blister steel and the large conical structures were a characteristic feature of the city's industrial landscape.

Because the ancients could not produce temperatures high enough to melt iron fully, the production of steel in decent quantities did not occur until the introduction of blister steel during the Middle Ages.

See: Cementation process This produced blister steel, which could be headed and hammered with wrought iron to make shear steel, which was used for cutting edges like scissors, knives and axes.