Working with Puddled Wrought Iron
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 homogeneous pure irons. Care must be taken to respect the properties of the material. It is necessary, when forging puddled iron always to do heavy forging at a high temperature – around 1350 to 1450 degrees Centigrade (bright to sparkling white heat). At these temperatures, the iron will move very quickly, whilst doing no damage to the grain structure.
Finishing work, bending etc., can be done at red heat. Should heavy working at lower temperatures result in splitting along the grain boundaries, it is necessary only to heat the iron to a welding temperature to close the split under the hammer. At a white heat it will be found that wrought irons are far softer to forge than even pure iron. This is due to the internal slags melting and providing an internal lubricant that reduces friction during distortion under the hammer.
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.
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. It is neither necessary nor recommended to galvanise or zinc spray wrought iron.
In the event of any further queries on working techniques advice is readily available from http:///www.realwroughtiron.com