Changes in the Iron-Refining Process
“Around the middle of the fourteenth century, an indirect process began to evolve utilizing blast furnace techniques. Essentially, in the foundry, a tower of some fifteen or twenty feet in height was carefully built, and iron ore was layered in with charcoal. A fire was lit, and, with the aid of powerful bellows blowing air into the mass through “tuyeres,” a hot fire was maintained to actually melt the ore, which collected in a pan at the bottom. Slag rose to the surface of the melt and was scraped off. The liquid iron was tapped off into “sows” and “pigs,” which were further refined and purified at the hearths in the bloomaries or “fineries” and “chaferies,” where the now malleable iron was reheated for welding and forming into finished bars. The finery and chafery, together, are often referred to as the forge stage. Later, rolling and slitting mills were invented to produce shapes making the production of small pieces such as nails easier. The English words foundry, finery, chafery, tuyere were all derived from the French counterparts.”[1]
A fair amount of skill on the part of the ironmaster, founder, or fyner, as the person in charge of a hearth or bloomerg the temperature was correct. He had to know how to structure the contents of the blast furnace to obtain the iron, judging carefully the quality of the ore, the quality of the charcoal, and impurities that would affect the finished product.[2]
The founder removed the slag with an iron hook known as a “chorchett” and guided the molten iron into sand molds where it hardened into “sows” and “pigs,” hence the name “pig iron” given to the product of the foundry.
The fyner worked at the finery hearth converting the pig iron from the foundry furnace into malleable iron. With furgons, long iron bars used for clearing the bottom and sides of the furnace and the tuyere hole, the fyner moved the melted-down pig iron to the top of the fire, so as to expose it to the decarburizing blast of the tuyere and with a “ranggarde” kept the molten matter in motion by stirring. Toward the end of the refining process, the ball of iron was taken out of the fire by tongs and an iron hook and moved to the hammer and anvil to be consolidated into the desired size and shape.[3]
Richard Lenard, son of Lawrence Lenard, left us a fireback, dated 1636, which shows not only himself as an ironworker and his dog, but hammer, baskets, wheelbarrow, hook, tools, weights, and ladle. Richard was an ironmaster and worked at the Brede Furnace in Sussex.
Important in the process was removing the impurities. Sulphur would make the iron brittle and not malleable, for example.
Organizing one of these early ironworks was no easy task. One had to obtain sources of ore and charcoal, plus the stone, wood, and iron to construct the furnaces, finery, chafery, hammer, and bellows. “It required several hundred bushels of charcoal and two weeks’ time to heat the furnace hot enough to smelt the ore. When started, the furnace could not be stopped conveniently until the blast of five or six months was completed. The workmen, in leather breeches, knew no regular weekdays or Sundays, but spent their time alternately at the furnaces and in the cook-shed, where tables were set day and night and the cook, with a big kettle full of meat and vegetables simmering upon the fire, was constantly at hand.”[4] Skilled workmen and tools were also required. Since an ironworks could consume an acre of woodland’s worth of charcoal each day it was “in heat,” rather substantial amounts of woodland were required, plus the labor to cut the wood, make the charcoal, and transport it to the ironworks. The enterprise could easily employ 100 to 250 men in all these tasks.
It is little wonder that literacy became essential in the overall operation of ironworks and why the clerk was the highest-paid position. Written records became necessary to account for payroll, to track loans, to track ownership of property and supplies, to measure and account for production, and to keep investors (termed “undertakers” in those days) informed. Such would explain why a Richard Leader was required to manage Lynn, rather than a master iron founder, and why Henry Leonard, who was an iron founder but illiterate, had so much difficulty with lawsuits in managing the Rowley works.
To this basic process were added technological refinements over the centuries. A flux material was added to the mix to collect impurities. Waterpower was applied to drive the bellows and the giant hammers which were used to remove impurities. Coal as a source of heat was perfected in the 1700s and widely applied in the 1800s.
“The first continuous and completely successful use of mineral fuel in the blast furnace was by Abraham Darby, of Shropshire, at his furnace at Coalbrookdale, in 1735, or possibly a year or two earlier.”[5] Actually, Dud Dudley successfully used coal to reduce iron ore in the early 1600s, but his iron contained too many impurities to become acceptable. Also, he was interrupted by the Civil War and many suits over the process.
Steel was made in England as early as 1609,[6] but “the invention of crucible cast steel originated with Benjamin Huntsman, an English clockmaker, at Sheffield, in 1740.”[7]
The use of anthracite coal in the smelting of iron ore, which took place about 1840, rendered the further production of charcoal pig iron unprofitable.[8] As the large smelters in Pittsburgh, Sparrows Point, Ohio, and on the shores of Lake Michigan began producing iron and steel in large quantities at lower costs, the small furnaces in New England were gradually driven out of business in the 1800s or forced to specialize in a particular product line.
[1] Robert E. Bowman, “Glimpses into the English and Continental Origins of Certain Braintree and Saugus Ironworkers of about 1650: Vinton, Leonard, Pray, Pinion, Tyler, and Russell,” The Essex Genealogist, May 2000, p. 2.
[2] E.N. Hartley, Ironworks on the Saugus: The Lynn and Braintree Ventures of the Company of Undertakers of the Ironworks in New England, Norman, OK: 1957, pp. 165-184, explains the process used in New England in the late 1600s.
[3] Dr. H. R. Schubert, “The First English Blast-Furnace,” Historical Note 37, the Journal of the Iron and Steel Institute, February 1952.
[4] Davol, “Two Men of Taunton,” p. 56.
[5] James Moore Swank, “History of the Manufacture of Iron in All Ages and Particularly in the United States from Colonial Times to 1891,” Philadelphia: The American Iron and Steel Association, 1892, p. 52.
[6] Swank, p. 54
[7] Swank, p. 54.
[8] Swank, p. 162.