Standing incongruously in a car-park, the Doncaster Street Cementation Furnace is a precious relic of the origins of Sheffield’s steel industry.
A cementation furnace is a distinctive conical structure, which resembles the bottle-kilns of the Staffordshire potteries and serves a similar function.
Swedish or Spanish bar-iron and charcoal, sandwiched like a layer cake, was heated to a temperature of 1,100-1,200°C in sealed sandstone vessels heated by an external coal fire.
The resulting product was called blister steel and was uneven in quality because the outer blistered surface of each bar was tougher than the core and no two bars were consistent.
The earliest surviving cementation furnace in Britain is the stone-built example at Derwentcote, Tyneside, dating from c1730.
The Sheffield furnace, dating from 1848, is the very last survivor of around 250 such furnaces which dotted the city until the end of the nineteenth century. It formed part of a group of five in the works of Daniel Doncaster & Sons.
It remains complete, with the hearth and the surrounding flues that directed the heat around the two parallel sandstone chests which contained alternate layers of charcoal and iron, sealed by a crust of “wheelswarf”, that is, debris from blade-grinding combined with sandstone dust.
Each firing produced up to 35 tons of steel.
The blackout mask on top of the conical chimney was added after it was damaged in the Sheffield Blitz.
When the rest of the works was demolished the new landowners, Midland Bank Ltd, now HSBC, fenced it off and restored it. It’s easily visible from the surrounding streets, and can be inspected more closely by picking up the key from Kelham Island Industrial Museum.
The Doncaster Street cementation furnace is included in the itinerary of the Sheffield’s Heritage (October 2nd-6th 2017) tour. For details, please click here.