How To Identify Wrought Iron
Wrought iron is unlike cast, in that it is not brittle, and will bend rather than break. For this reason, wrought ironwork is frequently far more delicate, although years of paint can obscure this. Cast iron is most frequently identified by its repetitive nature and forms, which could be carved into a wooden pattern, but not made by hammer and anvil.
Telling wrought iron from mild steel is often more difficult for the layman, as both will bend, and not break Frequently, however, work in mild steel is readily identified by the lower standards of workmanship often used. Look for evidence of electric welding, mild steel is often given away by more active corrosion, which tends to run out of the joints and stain paintwork and stonework. This is seldom the case with wrought iron.
Wrought iron may also be dated approximately by its texture. Until the very end of the eighteenth century, sections of wrought iron were derived by forging of billets by hand or waterpower; this resulted in a more or less uneven surface texture, and very sharp corners. A foreshortened view of a bar displays well the irregularities of the surface. Rolled bars, on the other hand, produced from the beginning of the nineteenth century, are perfectly smooth, and the corners can display a small radius. Nineteenth century wrought iron is known as ‘puddled iron’.
Tests for Wrought Iron:
Wrought Iron nick bend test
The sample is nicked by cold chisel or sawing to approximately half depth and doubled back cold to show the fracture. Wrought iron will exhibit a ‘green stick’ fracture, showing the grain, whereas steel will exhibit a smooth fracture plain.
Polish and examine for grain.
The sample is polished in a plane parallel to the length of the bar, and the exposed bright surface examined for signs of a grain caused by linear slag inclusions.
The sample is brought to an engineer’s grindstone and the resulting sparks examined for colour and nature. Typically a puddled Wrought Iron will exhibit a more or less dead reddish spark, whereas steel will have more or less bursting white sparks caused by the inclusion of carbon alloyed with the constituent iron. Charcoal irons, however may be confused with steel in this test as they frequently contain large amounts of carbon. Pure iron, while containing no carbon, can be identified by the absence of grain in the nick bend test.
Mike’s musical test.
The video below shows Mikes ability to test whether chain is iron or not with his unique musical approach which was much nicer than using a grinder although we are not able to guarantee its accuracy so had to do both tests. I am sure given more time and research he would have perfected this musical test.
Arek and Sam forging a square corner detail for the top rail of a wrought iron gate they are making. If you want to see more videos like this follow us on INSTAGRAM rollingwroughtiron READ MORE