Working with Trading Standards

OUR AIM: To assist Trading Standards officers, architects, those engaged in maintenance of heritage buildings and interested members of the public to distinguish between genuine Wrought Iron and the many ‘other iron’ and steel products often mistaken for Wrought Iron.

We at Chris Topp and several other blacksmiths have been working with Trading Standards for a number of years to try and make the general public more aware of what they are buying.

We also wish to promote and protect the genuine members of our industry involved in heritage work of repairing and replacement of ancient works of art.

Search the web and you will find 600,000 sites listed under Wrought Iron of which only a small fraction will be genuine Wrought Iron. Today the term Wrought Iron can mean almost any type of metal and any manner of construction from something you can buy in a local DIY store to the screens at Hampton Court by Jean Tijou. Ornamental ironwork is often referred to as Wrought Iron even though it is more likely to be made from mild steel. The difference in quality and value is enormous.

Unlike most other crafts in the heritage field, users and specifiers generally have little understanding of Wrought Ironwork. This is not altogether surprising as no BS standard or English Heritage guidance is available for Wrought Iron. Further, architects and related professionals are often not trained in the field and do not understand the difference between fabrication and traditional methods and between Wrought Iron and mild steel.

There is of course a major difference in quality and durability when restoring genuine Wrought Iron. Wrought Iron is known for its durability. Just look at the amount of Wrought Iron in heritage sites and buildings that is over 300 years old. Whereas it would be unthinkable to repair historic stonework with concrete and cast stone, it is not uncommon for historic Wrought Iron to be repaired using mild steel and electric welding.

We at Chris Topp would like to see an end to the use of the words ‘Wrought Iron’ when applied, as is so often the case, to products made from iron and mild steel.

WHAT IS GENUINE WROUGHT IRON

The word ‘wrought’ is the medieval past tense of the verb ‘to work’. As irregular past-tense forms in English have historically been phased out over long periods of time, ‘wrought’ became ‘worked’. Wrought Iron literally means ‘worked iron’.

The weathering properties of wrought iron are well known. While it does of course rust in time, with reasonable maintenance this can indeed by a very long time. On the other hand, steel is well known for its corrodibility, and the intricate forms that can produce water traps only encourage corrosion. Hence it is normal practice to coat steelwork with zinc, which does indeed delay corrosion, but neither galvanising nor zinc spraying can effectively be applied to complex forms.

Wrought Iron is best described as a two component metal consisting of high purity iron and iron silicate – a particular type of glass-like slag approximately 250,000 of these siliceous (slag) fibres appear in each cross-sectional square inch (25mm square) of good quality wrought iron. The iron and the slag are in physical association, as contrasted to the chemical alloy relationship that generally exists between the constituents of other metals. Wrought Iron is the only ferrous metal that contains siliceous slag.

Wrought Iron is unlike cast in that it is not brittle and seldom breaks. 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 in 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 the paintwork, where this is seldom the case with Wrought Iron.

There are essentially two types of Wrought Iron. Firstly, that used from the Iron Age to 1800, known as charcoal-iron, which was made in a charcoal fire. Secondly, the Wrought Iron of the industrial revolution called puddle-iron which was made from cast iron in an indirect coal fired furnace.

Wrought Iron can be approximately dated 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.

For those involved in conservation work it is therefore necessary to ensure that both the material and the working methods are properly specified in order to ensure accurate repairs and like-for-like quotations.

TESTING FOR GENUINE WROUGHT IRONS: We can help

We would use one or all of three methods, as detailed below, to determine the identity of their component metal. In most cases, the result will indicated that the items were made from mild steel and not Wrought Iron.

Tests for Wrought Iron;

1. 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.

2. 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.

3. Spark test. 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.