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The following statements are taken from an instruction sheet issued by The Real Wrought Iron Company entitled "Puddled Wrought Iron - Working Instructions". "Puddled iron is a mixture of nearly pure iron with up to 5% siliceous (glassy) slags which take the form of linear fibres - giving the metal its characteristic grain. Puddled iron is for the more advanced forger more so than steel or homogenous pure irons." Our Comment - Wrought iron, pure iron and steel are different materials, each with their own properties. There are also many other materials which can be forged including stainless steel and copper and they each provide the forge worker with different challenges. Some blacksmiths specialise in one material only and others use a variety but, like any other artists, their "advancement" in the craft is measured by the results they achieve in their chosen medium not by the choice of medium. "There is nothing to beat the forge-welding ability of puddled iron, as the enclosed slags form a natural flux, allowing the iron to be heated rather more than can pure irons or steel, this extends considerably the heat range over which the iron can be welded." Our Comment - This statement would appear to contradict the first statement with regard to ease of working and required skill levels. Pure iron is relatively easy to fire-weld and requires a similar temperature range to that required for wrought iron. No flux is required to fire-weld pure iron because the material is homogenous and easily bonds with itself. "Wrought iron is the traditional material of the blacksmith. Due to the siliceous slags combined with its fibrous structure, it resists corrosion far better than modern steels or pure irons, as is amply shown by the survival of much of our heritage of wrought ironwork, in many cases centuries old." Our Comment - There is powerful evidence that pure iron was used extensively by the Romans for armour etc. although it is not yet known how they produced it. Wrought iron was a much later invention, apparently the result of efforts by the smelters to remove the unwanted slag from the iron after smelting. Wrought iron is marginally better than mild steel at resisting corrosion but pure iron is 22% better. See Corrosion Test . All iron and steel rusts sooner or later if exposed to the atmosphere. The longevity of any particular item depends largely on the amount of TLC it has received over the years. If the elements can be kept away from the metal by a well-maintained paint finish it will not be able to rust. The Forth Railway Bridge is made from mild steel and has survived for over 100 years because the paint finish is maintained on a regular basis. Perhaps less well known is the fact that the Eiffel Tower, which is a similar age and made from wrought iron, is also subject to regular repainting. Despite this care and attention the Tower has been extensively repaired in pure iron, the material of choice for restoration work in France. "It is neither necessary or recommended to galvanise wrought iron." Our Comment - It would be beneficial to be able to galvanise wrought iron as with any ferrous metal but we agree that it should not be recommended. This is because there is a serious risk of it exploding in the galvanising bath. To read more about the use of various metals in restoration click on the title bar below. |
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