Wrought Iron - from the Romans to today
Posted: Sunday, February 20, 2005
by lorien1973
Online Discount Mart Home & Garden Decor
What is 'Wrought Iron'?
Wrought iron is a pure form of commercial iron, with a very low carbon content. It is malleabel, touch but not brittle, ducticle and easily welded. However, it is too soft to make blades from, in which case steel or cast iron are used. Wrought iron has been used for thousands of years, and represents the "'iron' that is referred to throughout history.
Wrought iron is considerably more delicate than cast iron, is not brittle and therefore rarely breaks. In terms of malleability wrought iron can look very similar to 'mild' steel. There are two primary methods to distinguish them firstly, by 'mild' steels increased tendency to corrode and, secondly, by the way in which they've been used. Ornamental use of wrought iron generally requires a higher degree of craftsmanship, and is certainly more likely to be found in older pieces.
A Short History of Wrought Iron
The period of time known as The Iron Age began in about 1000 BC, although the true history of iron is known to date back to 300 BC where Egyptians used it to make axes and chisels.
Early iron would have been very brittle, as the process of reducing the carbon content through melting, re-melting and hammering the ingots, had not yet been mastered. The use of wrought iron continued to increase throughout the Middle Ages, initially for construction and weaponry and, later, in an ornamental fashion on churches and monasteries. Notre Dame in Paris and the Winchester Cathedral in England are thought to be two of the earliest examples of ornamental iron use. There are wrought iron railings in Westminster Abbey, in London, dating back to the 13th century.
The iron used by blacksmiths until the 1700's was actually quite structurally different to the iron used in modern day construction and furnishings. Nowadays most wrought iron is a carbon alloy if iron, with a carbon content of between 2 and 6%. In those days the carbon content was closer to .0.04% and was comparatively soft and malleable.
The end of the 17th century marked the beginning of the great age of British ironwork, influenced by the French Baroque style. Initially, wrought iron was less popular that cast iron, likely due to the need to make wrought iron from hand and the associated higher cost.
The structural use of iron only really began in a widespread fashion in the late 18th century with English Iron-Master Abraham Darby's first Iron Bridge, made entirely of iron the bridge had to be made in parts and assembled at the building site.
The use of wrought iron trusses in combination with cast iron columns led to the creation of the first large scale iron buildings without supporting masonry. This began in the second quarter of the 19th century with the use of cast iron columns with wrought iron trusses in the construction of the Crystal Palace in London in 1851. The trusses made it possible to replace masonry arches and vaulting between the vertical supports and create buildings with wider spans and large internal spaces.
Wrought iron was originally produced by a method known as 'bloomery,' named for the the 'iron bloom' that was produced. The process involved using smelters cheated be charcoal, into which the ore would be poured, then covered with charcoal. The heat produced would melt the ore and as the ore melted it would release oxygen, which would mix with the charcal to release carbon dioxide. Hence, little carbon entered the iron directly. The resulting 'iron bloom,' which comprised iron and silicates, would be worked to remove the slag and impurities. This process gave rise to the name 'wrought' iron, as the iron was pounded and twisted.
In the early 18th century changed ironmaking forever with the introduction of the blast furnace replaced charoal with coke, which proved to be both less expensive and more efficient. The product of this process was known as 'pig iron' and over time the process of 'faggoting' was developed in order to convert the pig iron to a more workable product. As iron production rose, prices slumped.
Then, in 1856 Henry Bessemer invented the Bessemer Converter, which enabled steel to be produced more cheaply than ever before. Unlike wrought iron, steel containedo slag and hada higher carbon content than wrought iron, making it harder. With the increased use of this 'mild' steel, which could be mass-produced far more cheaply than wrought iron, by the late 19th century wrought iron was in decline.
Since this decline, however, wrought iron has enjoyed something of a renaissance in more recent years. Although wrought iron will never be utilized in such a widespread fashion again it continued to be popular for ornamental purposes, from gates and railings to candlesticks and wine racks. There will always be those who appreciate the artistry involved in using wrought iron to create beautiful things.
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