THE ROBERTSBRIDGE PROJECT

Iron & Steel making at Robertsbridge

In 1541 when Sir William Sidney built a blast furnace at Robertsbridge, this was an early venture into new technology imported from the southern part of Belgium via the Pays de Bray in northern Normandy. This blast furnace technology adopted in the Weald came from French speaking Walloons who had adapted water powered bloomery furnaces producing a solid iron product which could be readily forged, but which had a poor yield and hence low output. The change was to produce molten iron which gave a much higher yield and could be cast into useful but rather brittle ‘cast iron’ items, but required refining in a forge to lower the carbon content if more ductile products such as those produced in bloomeries were required.

At the time Sir William embarked on the venture there were only eight blast furnaces operating in the Weald, all in present day East Sussex. The first, Queenstock at Buxted had been built in 1490. By the end of the Wealden blast furnace era, which closed with Ashburnham furnace in 1813, 115 furnaces had been built. Sir William may be considered unlucky in his choice of Robertsbridge for his venture as the ore in the area is contaminated with gypsum (CaSO4) - indeed the mineral is mined in the area today. This introduced sulphur into the iron from the blast furnace which restricted its use in the forge to making only small items, such as nails. Indeed, the furnace was closed for 27 years with iron being sourced from Panningridge where he also built a furnace. However, Robertsbridge did supply him with wood for charcoal - the fuel and reducing agent for the furnace, and fuel for the forge as well as water systems to power the furnace and forge bellows and forge hammers and a nearby navigable river ? the Rother ? for transport to and from the port of Rye.

William’s son, Sir Henry Sidney further developed the technology by introducing steelmaking by the ‘German method’ in which the blast furnace iron is only partially decarburised - lowering the carbon content of the blast furnace iron from about 4%C to 1%C or less. For this, he again relied on imported technology bringing in ‘Dutch’ (German) workers to operate the forges. However, they found the local iron to be unsuitable for steelmaking and preferred to use Welsh iron so requiring Sir Henry to lease a blast furnace in Glamorganshire from where iron plate was shipped by sea and then up the river Rother to the steel forges. The Sidneys owned the ironworks for four generations, selling it to Sir Thomas Webster in 1726. During Webster’s tenure gun founding commenced - a lucrative product in times of war and one that many Wealden furnaces were engaged in by this time.

In 1747, a later tenant of Webster, the Jukes brothers, build an air furnace to melt iron. This reverberatory furnace requires no bellows, relying on a chimney to create a draught to burn the fuel which, unlike a forge, is not in contact with the iron being melted but is in an adjacent chamber - the hot gases from the fuel passing over the iron melts it. This allows cheaper coal rather than charcoal to be used as fuel, but there is no evidence that the Jukes ever used coal which would have had to be imported many miles from the Midlands. An air furnace, however, provided the option to ‘blend’ cast and wrought iron and was convenient for making small objects including cannon balls and shot.

In 1756, a Staffordshire ironmaster, John Churchill, held the lease and signed agreements to provide ordnance to the government, but lost the contract five years later. By 1767 he was bankrupt.

The final phase of operation was in the hands of James Bourne, a relative of Churchill, who operated the furnace for a short time, then just the forge, producing a mere 50 tons of bar iron a year until operations ceased around 1793.

Tim Smith

©   Wealden Iron Research Group 2014