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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 th ...
used to produce
wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag inclusions (up to 2% by weight), which give it a wood-like "grain" ...
from
pig iron Pig iron, also known as crude iron, is an intermediate product of the iron industry in the production of steel which is obtained by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with ...
by decarburization 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, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
. 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 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 product of the iron industry in the production of steel which is obtained by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with ...
fined into wrought iron and
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistan ...
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 () was an era in History of China#Ancient China, ancient Chinese history characterized by warfare, as well as bureaucratic and military reforms and consolidation. It followed the Spring and Autumn period and concluded ...
(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 oxides. The bloomery was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called a ''bloom' ...
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 ( , ; ; Chinese postal romanization, alternately romanized as Shantung) is a coastal Provinces of China, province of the China, People's Republic of China and is part of the East China region. Shandong has played a major role in His ...
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, ...
until the 15th century, as described in conjunction with the
waterwheel A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel (usually constructed from wood or metal), with a number of blades or bucke ...
-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 elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...
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,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic countries, Nordic c ...
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 at least a horizontal hearthstone and often enclosed to varying degrees by any combination of reredos (a lo ...
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. On the small uninhab ...
north of
Stockholm Stockholm () is the capital and largest city of Sweden as well as the largest urban area in Scandinavia. Approximately 980,000 people live in the municipality, with 1.6 million in the urban area, and 2.4 million in the metropo ...
and certain adjacent provinces, another kind known as the
Walloon forge A Walloon forge (or Walloon process) is a type of finery forge that 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 15th century. ...
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 W ...
, which was exported to England to make blister steel. Its purity depended on the use of ore from the
Dannemora mine The Dannemora mine (''Dannemora gruvor'') at Dannemora in Uppsala County, Sweden was once one of the most important iron ore mines in Sweden. The mine was closed by its owners SSAB in 1992. It may have been open since the 13th century, but ...
. 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 A chafery is a variety of hearth used in ironmaking for reheating a bloom of iron, in the course of its being drawn out into a bar of wrought iron. The equivalent term for a bloomery was string hearth, except in 17th century Cumbria, where the ...
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 product of the iron industry in the production of steel which is obtained by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with ...
so as to oxidise the carbon (and silicon). This produced a lump of iron (with some
slag Slag is a by-product of smelting ( pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-p ...
) known as a bloom. This was consolidated using a water-powered hammer (see
trip hammer A trip hammer, also known as a tilt hammer or helve hammer, is a massive powered hammer. Traditional uses of trip hammers include pounding, wikt:decorticate, decorticating and polishing of grain in agriculture. In mining, trip hammers were used f ...
) 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 and metropolitan county in the Yorkshire and Humber Region of England. The county has four council areas which are the cities of Doncaster and Sheffield as well as the boroughs of Barnsley and Rotherham. ...
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 A chafery is a variety of hearth used in ironmaking for reheating a bloom of iron, in the course of its being drawn out into a bar of wrought iron. The equivalent term for a bloomery was string hearth, except in 17th century Cumbria, where the ...
. 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, ...
(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