Wrought Iron

There are two ways of viewing wrought iron: The public conception which is a metal (any metal), usually painted black, and has some twists in it; The metallurgical/blacksmith conception which is iron ore processed in a certain way, resulting in a material that is a combination of iron and iron silicate (commonly referred to as: slag). The slag is distributed though out the iron as fibers, giving the iron the appearance of having a "grain" to it. The finer the fibers and more evenly distributed the fibers, the higher the quality of the wrought iron. For a blacksmith who frequently demonstrates in front of the public this is a topic that comes up frequently.

One of the best ways to identify wrought iron is via a spark test: in dim light, touch an angle grinder to the material or the material to a bench grinder and look at the sparks given off; they should be very short, reddish-yellow and no stars or forks. (Compare the wrought iron sparks to the sparks given off by a known piece of steel, using the same pressure and under the same light conditions.) Unfortunately, this is considered a destructive test as it will leave a grind mark on the item being tested. If you are testing a wagon wheel, no big deal, but if it is a finely forged item, such as a flesh fork you probably do not want to do this. With the advent of battery powered angle grinders, now you can take the grinder to the likely wrought iron out in the field, test it, and then drag it home if it infact is wrought iron. Where as before, you had to bring the metal back to the shop and then test to see if you had infact scored some wrought iron or not. Unfortunately, there is no way to distinguish between a nicely forged piece of ironwork made out of wrought iron as compared to the same item forged from steel simply by looking at it.

Wrought iron was produced in a number of levels of quality: single refined, double reined; and triple refined. In each of these types of wrought irong, the layers of slag are thinner and more finely distributed through the iron. The single refined is the crudest. It was used for structural purposes. Often wagon tires are made from single refined wrought iron. Your finest items: pipe tongs, flesh forks, sugar nippers, etc would have been made from the triple refined iron. Other items would have fallen between the two extremes and would have been made from double refined iron. There is no way to tell whether you have single, double or triple refined iron without putting it in the forge and hammering on it.

Wrought iron that has been out in the weather for very long periods takes on a very distinctive corrosion pattern. The iron molecules rust away, leaving the layers of slag, resulting in something that looks like wood grain. The best examples of this can be found at maritime museums. The salty sea air really does a number on the old wrought iron artifacts, such as anchors, etc.

• Example of well corroded wrought iron:
  

A source for "new" wrought iron in England is: http://www.realwroughtiron.com/index.asp

At most hammer-ins, you will usuallly find someone in the tailgate section who is selling salvaged wrought iron. One of the problems is that there is no way to tell what quality it is. Also, often it is in fairly large sections. So if you do not have access to a power hammer, you will have some hard work ahead of you getting the iron down to a usable size.

When it comes to forging the wrought iron, you want to work it at a very high heat, yellow into white. In fact what you will be doing, is welding it back to itself as you work it. If you forge it below yellow heat, you will often find the wrought iron splitting and/or delaminating. Single refined is more likely to do this than double or triple refined. One nice feature of wrought iron, is that it forge welds much easier than mild steel does. No need for flux.

If you make items out of wrought iron, you need to take the "grain" of the iron into consideration in your design. Just as you take the grain of a piece of wood into consideration, you must pay attention to which way the "grain" of the iron runs. For example, if you are making a lifting hook out of steel, you can just punch the eye of the hook. If you are using wrought iron, you need to wrap the lifting end of the hook around a mandrel and weld it. If you were to just punch the eye as you did with the mild steel, there would be a weak spot at the top of the eye.

-- AlbinDrzewianowski - 09 Aug 2009