Saltford Brass Mill retains the shell of an annealing furnace.
Annealing furnaces would have been a feature of the brass mills at Keynsham, Weston, Woollard, Bitton and Kelston, as well as at Saltford. The remains of these once common structures can be seen at Kelston and Saltford, with Saltford being the only one open to the public.
The brass produced in Bristol was malleable and ductile, enabling it to be cold worked, i.e. rolled into sheets or hammered into hollowware while at room temperature. However, excessive cold working broke down its grain structure, making the metal brittle which caused it to crack if worked further. To enable continued working, the brass needed to be annealed, that is heated to between 340oC and 370oCo to allow the grain structure to reform and restore its malleability. The annealing furnaces provided a controlled heated environment to perform this process.