A forge at Derwentcote, Co Durham, was built in c1719, and operated until 1891. The cementation steel furnace which is the main subject of this report was probably added in c 1733, and remained in use until between 1875 and 1891. The works was operated by a series of relatively short-lived partnerships in the eighteenth century; from the 1790s to 1872 it was controlled by successive members of the Cookson family, and from 1872 to final closure in 1891 it was again operated by a series of short-lived partnerships and companies.

Externally, the furnace consists of a buttressed rectangular structure, passing up into a conical chimney. Internally, it contains an ashpit at the base, above which a firegrate opens into the base of a rectangular vaulted chamber containing the stone cementation chests. Flames from the fire were carried by a series of flues round these chests, and exhausted by a second series of flues into the base of the hollow chimney. The stone external structure is original, but most of the internal linings represent repairs and replacements during the working life of the furnace.

The interiors and surroundings of the buildings attached to the furnace have been excavated, in advance of public display. Within the Southern Building, this excavation revealed a series of floor levels, with evidence for smithing and for a charcoal-grinding mill. Outside the standing buildings, excavation revealed the sites of one paced yard and three timber buildings (two of which had been walled with brick panels infilling a timber frame, whereas the third had been entirely of timber construction), together with stratigraphic sequences relating to the construction, use, and abandonment of the furnace.

The large finds assemblage was derived largely from post-abandonment contexts, and was dominated in bulk by firebrick and process residues. The former included an interesting series of stamps, and the latter forms a type-assemblage for process residues from the cementation process. The ironwork assemblage included fittings from various parts of the furnace. The furnace has now been conserved and opened to the public by English Heritage.