© Copyright Helen Wilkinson and licensed for reuse
under
this Creative Commons Licence.
Close by the banks
of the River Derwent near the village of Hamsterley Mill can be found a rather important relic of
the Industrial Revolution: the Derwentcote Steel Furnace. It is the oldest and
best example of its type remaining in the world – a cementation furnace which
turned wrought iron into high grade steel.
Of the remains
that can be seen today on the site, the oldest parts date to at least as early
as 1719; and the plant remained in use until 1891 when a more advanced form of
steel production was developed. As for Derwentcote, it began as a forge (and
mill) around 1719, with the furnace added c.1733. Various storage buildings
were then added as the complex hit full pelt. Iron would be imported from Sweden , via the Derwent, and handy local
resources (charcoal, coal, clay and sandstone) made it a perfect spot for its
intended purpose.
The cementation
process involved layering bands of iron bars and charcoal powder in the central
cone. A fire was lit and the temperature raised to about 1,100°C in the sealed chambers, causing the
carbon from the charcoal to diffuse into the iron. The whole process –
including the cooling period – took three weeks, and produced 10 tons of
‘blister’ steel. The steel was then taken to the water-powered forge to be made
into items such as tools – steel, of course, being preferable to iron due to
its combined strength and flexibility.
For a time
Derwentcote and the Derwent Valley were the epicentre of the British steel industry, but
progress eventually overtook it. After it fell out of use the building endured
a century of slow decline – until English Heritage restored it in 1990.
Currently an
archaeological programme of investigation is examining a nearby row of ruinous
cottages thought to have been occupied by the families of the furnace workers.
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