Finery forge
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A finery forge is a
forge A forge is a type of hearth used for heating metals, or the workplace (smithy) where such a hearth is located. The forge is used by the smith to heat a piece of metal to a temperature at which it becomes easier to shape by forging, or to the ...
used to produce
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.05%) in contrast to that of cast iron (2.1% to 4.5%), or 0.25 for low carbon "mild" steel. Wrought iron is manufactured by heating and melting high carbon cast iron in an ...
from
pig iron Pig iron, also known as crude iron, is an intermediate good used by the iron industry in the production of steel. It is developed by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with si ...
by
decarburization Decarburization (or decarbonization) is the process of decreasing carbon content, which is the opposite of carburization. The term is typically used in metallurgy, describing the decrease of the content of carbon in metals (usually steel). Decar ...
in a process called "fining" which involved liquifying cast iron in a fining hearth and removing carbon from the molten cast iron through
oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...
. Finery forges were used as early as the 3rd century BC in China. The finery forge process was replaced by the puddling process and the roller mill, both developed by
Henry Cort Henry Cort (c. 1740 – 23 May 1800) was an English ironware producer who was formerly a Navy pay agent. During the Industrial Revolution in England, Cort began refining iron from pig iron to wrought iron (or bar iron) using innovative productio ...
in 1783–4, but not becoming widespread until after 1800.


History

A finery forge was used to refine wrought iron at least by the 3rd century BC in ancient China, based on the earliest archaeological specimens of
cast Cast may refer to: Music * Cast (band), an English alternative rock band * Cast (Mexican band), a progressive Mexican rock band * The Cast, a Scottish musical duo: Mairi Campbell and Dave Francis * ''Cast'', a 2012 album by Trespassers William ...
and
pig iron Pig iron, also known as crude iron, is an intermediate good used by the iron industry in the production of steel. It is developed by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with si ...
fined into wrought iron and
steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...
found at the early Han dynasty (202 BC – 220 AD) site at Tieshengguo.Pigott, Vincent C. (1999). ''The Archaeometallurgy of the Asian Old World''. Philadelphia: University of Pennsylvania Museum of Archaeology and Anthropology. , p. 186-187. Pigott speculates that the finery forge existed in the previous
Warring States period The Warring States period in history of China, Chinese history (221 BC) comprises the final two and a half centuries of the Zhou dynasty (256 BC), which were characterized by frequent warfare, bureaucratic and military reforms, and ...
(403–221 BC), because of the wrought iron items from China dating to that period and there was no documented evidence of the
bloomery A bloomery is a type of metallurgical furnace once used widely for smelting iron from its iron oxides, oxides. The bloomery was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called ...
ever being used in China. Wagner writes that in addition to the Han dynasty hearths believed to be fining hearths, there is also pictorial evidence of the fining hearth from a
Shandong Shandong is a coastal Provinces of China, province in East China. Shandong has played a major role in Chinese history since the beginning of Chinese civilization along the lower reaches of the Yellow River. It has served as a pivotal cultural ...
tomb mural dated 1st to 2nd century AD, as well as a hint of written evidence in the 4th century AD Daoist text '' Taiping Jing''. In Europe, the concept of the finery forge may have been evident as early as the 13th century.Williams, Alan R. (2003). ''The Knight and the Blast Furnace: a History of the Metallurgy of Armor in the Middle Ages & the Early Modern Period''. Leiden: Brill. , pp 883. However, it was perhaps not capable of being used to fashion
plate armor Plate armour is a historical type of personal body armour made from bronze, iron, or steel plates, culminating in the iconic suit of armour entirely encasing the wearer. Full plate steel armour developed in Europe during the Late Middle Ages, e ...
until the 15th century, as described in conjunction with the
waterwheel A water wheel is a machine for converting the kinetic energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a large wheel (usually constructed from wood or metal), with numerous blade ...
-powered blast furnace by the Florentine Italian engineer Antonio Averlino (c. 1400 - 1469).Williams, Alan R. (2003). ''The Knight and the Blast Furnace: a History of the Metallurgy of Armor in the Middle Ages & the Early Modern Period''. Leiden: Brill. , pp 883-84. The finery forge process began to be replaced in Europe from the late 18th century by others, of which puddling was the most successful, though some continued in use through the mid-19th century. The new methods used mineral fuel (
coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...
or coke), and freed the iron industry from its dependence on wood to make charcoal.


Types

There were several types of finery forges.


German forge

The dominant type in
Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
was the German forge, which had a single
hearth A hearth () is the place in a home where a fire is or was traditionally kept for home heating and for cooking, usually constituted by a horizontal hearthstone and often enclosed to varying degrees by any combination of reredos (a low, partial ...
that was used for all processes.


Walloon forge

In Swedish
Uppland Uppland is a historical province or ' on the eastern coast of Sweden, just north of Stockholm, the capital. It borders Södermanland, Västmanland and Gästrikland. It is also bounded by lake Mälaren and the Baltic Sea. The name literally ...
north of
Stockholm Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...
and certain adjacent provinces, another kind known as the
Walloon forge A Walloon forge (or Walloon process) is a type of finery forge that decarburization, decarbonizes pig iron into wrought iron. The process was conceived in the Liège region, and from there extended to France, then England around the end of the ...
was used, mainly for the production of a particularly pure kind of iron known as
oregrounds iron Oregrounds iron was a grade of iron that was regarded as the best grade available in 18th century England. The term was derived from the small Swedish city of Öregrund, the port from which the bar iron was shipped. It was produced using the Wa ...
, which was exported to England to make
blister steel The cementation process is an obsolete technology for making steel by carburization of iron. Unlike modern steelmaking, it increased the amount of carbon in the iron. It was apparently developed before the 17th century. Derwentcote Steel Furn ...
. Its purity depended on the use of ore from the Dannemora mine. The Walloon forge was virtually the only kind used in Great Britain. The forge had two kinds of hearths, the finery to finish the product and the chafery to reheat the bloom that was the raw material of the process.


Lancashire forge


Process

In the finery, a workman known as the "finer" remelted
pig iron Pig iron, also known as crude iron, is an intermediate good used by the iron industry in the production of steel. It is developed by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with si ...
so as to oxidise the carbon (and silicon). This produced a lump of iron (with some
slag The general term slag may be a by-product or co-product of smelting (pyrometallurgical) ores and recycled metals depending on the type of material being produced. Slag is mainly a mixture of metal oxides and silicon dioxide. Broadly, it can be c ...
) known as a bloom. This was consolidated using a water-powered hammer (see
trip hammer Trip may refer to: Arts and entertainment Books Fictional characters * Trip (Pokémon), Trip (''Pokémon''), a ''Pokémon'' character * Trip (Power Rangers), in the American television series ''Time Force Power Rangers'' * Trip, in the 2013 film ...
) and returned to the finery. The next stages were undertaken by the "hammerman", who in some iron-making areas such as
South Yorkshire South Yorkshire is a Ceremonial counties of England, ceremonial county in the Yorkshire and the Humber region of England. It borders North Yorkshire and West Yorkshire to the north, the East Riding of Yorkshire to the north-east, Lincolnshire ...
was also known as the "stringsmith", who heated his iron in a string-furnace. Because the bloom is highly porous, and its open spaces are full of slag, the hammerman's or stringsmith's tasks were to beat (work) the heated bloom with a hammer to drive the molten slag out of it, and then to draw the product out into a bar to produce what was known as anconies or bar iron. In order to do this, he had to reheat the iron, for which he used the chafery. The fuel used in the finery had to be
charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ca ...
(later coke), as impurities in any mineral fuel would affect the quality of the iron.


Slag

The waste product was allowed to cool in the hearth and removed as a "mosser". In the Furness district they were often left as the capstone of a wall, particularly near Spark Bridge and Nibthwaite forges.


References


Sources

*H. Schubert, ''History of British Iron and Steel Industry c.450 BC to AD 1775'' (1957), 272–291. *A. den Ouden, "The Production of Wrought Iron in Finery Hearths", ''Historical Metallurgy'' 15(2) (1981), 63–87 and 16(1) (1982), 29–33. *K-G. Hildebrand, ''Swedish Iron in the Seventeenth and Eighteenth Centuries: Export Industry Before Industrialization'' (Stockholm 1992). *P. King, 'The Cartel in Oregrounds Iron: Trading in the Raw Material for Steel During the 18th century", ''Journal of Industrial History'' 6 (2003), 25–48. {{Iron and steel production Steelmaking Belgian inventions Chinese inventions German inventions Iron Metallurgical processes Metalworking