Afinery forge is aforge used to producewrought iron frompig iron bydecarburization in a process called "fining" which involved liquifying cast iron in a fining hearth andremoving carbon from the molten cast iron throughoxidation.[1] Finery forges were used as early as the 3rd century BC in China.[1] The finery forge process was replaced by thepuddling process and the roller mill, both developed byHenry Cort in 1783–4, but not becoming widespread until after 1800.[2]
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 ofcast andpig iron fined into wrought iron andsteel found at the early Han dynasty (202 BC – 220 AD) site at Tieshengguo.[1] Pigott speculates that the finery forge existed in the previousWarring States period (403–221 BC), because of the wrought iron items from China dating to that period and there was no documented evidence of thebloomery ever being used in China.[1] 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 aShandong tomb mural dated 1st to 2nd century AD, as well as a hint of written evidence in the 4th century AD Daoist textTaiping Jing.[3]
In Europe, the concept of the finery forge may have been evident as early as the 13th century.[4] However, it was perhaps not capable of being used to fashionplate armor until the 15th century, as described in conjunction with thewaterwheel-powered blast furnace by the Florentine Italian engineerAntonio Averlino (c. 1400 - 1469).[5] The finery forge process began to be replaced in Europe from the late 18th century by others, of whichpuddling was the most successful, though some continued in use through the mid-19th century. The new methods used mineral fuel (coal orcoke), and freed the iron industry from its dependence on wood to make charcoal.
There were several types of finery forges.
The dominant type inSweden was the German forge, which had a singlehearth that was used for all processes.
In SwedishUppland north ofStockholm and certain adjacent provinces, another kind known as theWalloon forge was used, mainly for the production of a particularly pure kind of iron known asoregrounds iron, which was exported to England to makeblister steel. Its purity depended on the use of ore from theDannemora mine. The Walloon forge was virtually the only kind used in Great Britain.
The forge had two kinds of hearths, thefinery to finish the product and thechafery to reheat the bloom that was the raw material of the process.
In the finery, a workman known as the "finer" remeltedpig iron so as to oxidise the carbon (and silicon). This produced a lump of iron (with someslag) known as abloom. This was consolidated using a water-powered hammer (seetrip hammer) and returned to the finery.
The next stages were undertaken by the "hammerman", who in some iron-making areas such asSouth Yorkshire 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 thento draw the product out into a bar to produce what was known as anconies orbar iron. In order to do this, he had to reheat the iron, for which he used thechafery. The fuel used in the finery had to becharcoal (later coke), as impurities in any mineral fuel would affect the quality of the iron.
The waste product was allowed to cool in the hearth and removed as a "mosser".[6] In the Furness district they were often left as the capstone of a wall, particularly near Spark Bridge and Nibthwaite forges.
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