EXPERIMENTAL BLOOMERY IRONMAKING
in the Weald of Southern England in the 21st Century
The Weald is an area of land in southern England stretching approximately 160km E-W and varying from 30 to 55km N-S. It lies within the three counties of Kent, Sussex and Surrey, stretching from the coast at Hythe in the east to a little beyond Haslemere in the west. Geologically it consists of deposits of clay and sandstone, located between the chalk hills of the North and South Downs. The name 'Weald' is derived from the German word meaning 'forest' which reflects the abundance of one of the raw materials needed for early ironmaking, wood to make charcoal.
From the late Iron Age until the end of the Middle Ages, iron was smelted in the Weald in bloomery furnaces. Nearly 600 bloomery sites are known in the Weald, and it has been possible to ascribe an approximate date to about a quarter of these. About 60% of these dated sites are from the period of the Roman occupation, and occur between 43 - 300AD.
OUR EXPERIMENTAL PURPOSE
The Wealden Iron Research Group (WIRG) is conducting a programme of experiments intended to replicate the bloomery smelting process used in the Weald during the Roman occupation. What follows is a description of the materials and processes used, together with analyses of the ore and products.
We are not just interested in producing iron. We are also attempting to produce slags which are similar in appearance and composition to the ancient slags we find in the field, using a furnace similar to that believed to have been used by the Romans.
This report, compiled in January 2003, is part of an ongoing project conducted by the smelting team of the Wealden Iron Research Group in an attempt to reproduce the techniques used to make iron in early shaft furnaces of the type believed to be operated in the Roman period.
To date, we have produced tap slags of similar composition to those found in the field, but we have not yet produced the high densities generally exhibited by these ancient slags. Our trials produce a more porous and friable material of a type occasionally found in the field.
While we are confident of producing iron and slag we are currently establishing the upper and lower limits of blowing rates and charge compositions which will produce a bloom and a dense slag.
TAKING PART If you would like to see what goes on and/or join the team, please contact Brian Herbert for more details.
Thanks are due to the 'smelting team' who operate and maintain the furnace and to London & Scandinavian Metallurgical Ltd, The University of Surrey, and English Heritage, for analysis and consultation on ore and slag samples.
Continue to: The ORE
© Wealden Iron Research Group 2003