Potting and stamping

Potting and stamping is a modern name for one of the 18th century processes for refining pig iron without the use of charcoal.

Inventors

The process was devised by Charles Wood of Lowmill, Egremont in Cumberland and his brother John Wood of Wednesbury and patented by them. The process was improved by John Wright and Joseph Jesson of West Bromwich, who also obtained a patent.

Process

The process involved the melting of pig iron in an oxidising atmosphere. The metal was then allowed to cool, broken up by stamping, and washed. The granulated iron was then heated in pots in a reverberatory furnace. The resultant bloom was then drawn out under a forge hammer in the usual way.

Adoption

During the 14-year term of the patents, the process was little used except by the inventors. However, from c.1785, shortly before Wright & Jesson's process came out of patent, it seems to have been adopted by many ironmasters in the West Midlands.

Ultimately, the process was replaced by puddling, though it remains unclear how quickly.