Wrought Iron Architectural Metalwork
Designed & manufactured in the U.K
By: Chris Topp & Co Ltd, North Yorkshire
Tel: 01845 501415
This section provides information and advice on the conservation and restoration of historic ironwork as, unlike most other crafts in the heritage field, there is little available guidance. Our aim is to help preserve an important part of our heritage by assisting those engaged in the maintenance of heritage buildings, and interested members of the public to;
"Wrought iron" does not mean ornamental ironwork!
Wrought iron is actually a material, not a descriptive term for items made in iron.
Wrought iron is the forgeable ferrous material made until about the mid-twentieth century that has been replaced by modern mild steel. It was originally called "wrought" ("worked") to distinguish it from cast, or poured iron, because its manufacture required extensive forming under power hammers and through rollers.
It is characterised by its composite nature: it is fibrous, like wood, though you cannot tell that by looking at it unless it has been broken or badly corroded. The fibrous material is iron silicate, intimately mingled with the iron, and it gives wrought iron a combination of resistance to corrosion, plasticity when hot and tensile strength when cold that are generally greater than in mild steel.
The carbon content is typically very low and the old iron welds beautifully with just incandescent heat and the hammer. It was expensive to make, and variable in quality. It did not lend itself well to high-speed production processes, but some smiths still seek out scrap wrought iron, or buy reprocessed wrought iron, because they prefer it to mild steel.
Welding Information
We are often asked about welding wrought iron, please click on this link that explains more. Link published with the kind permission of Malcolm at Mid Welding the DIY Guide.
The properties of cast and wrought iron
Cast and wrought iron have distinctly different properties that have dictated the ways that they have been used.
Cast and wrought iron can be identified by their built-in properties and by the way they have been used. An important distinction is carbon content, which is greater than 2% in cast iron but almost nil in wrought iron, which is virtually chemically pure iron. Cast iron is brittle and is strong in compression but weak in tension. Wrought iron is fibrous in texture, highly ductile and strong in both tension and compression.
The types of component that were made from cast and wrought iron were determined by the methods of manufacture and shaping as well as by the physical properties of the materials.
Cast Iron because shaped by pouring the hot liquid metal into a mould and as a consequence of its high liquidity in the molten state, it is well-suited to the production of components, both structural and decorative, of intricate shape. It can be subject to blemishes and flaws, hence the warning made by a 19th century ironwork contractor: "It is not the masses of metal that constitute strength, but the judicious proportions and forms of the casting".
Wrought iron is rolled in the final stage of production so it usually occurs in simple shapes of constant section - plates, bars and rounds. Its manufacture is carried out in small batches - up to 50 kg. at a time. This means that individual components are relatively small. It can be fire welded or riveted to make up large elements.
The production of wrought iron in Britain ceased in 1973, so what is marketed today under that name is either old material recycled or mild steel masquerading as iron.
Wrought Iron Technical & Specification Downloads
Chris Topp & Company whilst a commercial operation endeavours to provide both education and technical advice on historic ironwork in order to endeavour to raise awareness and raise the standard of restoration and thereby preserve an important part of our heritage. To this end various advice and information is available in Adobe Acrobat PDF format which is free for use by conservation officers, blacksmiths, educational bodies, architects and members of the public.
You are welcome to use this material as you see fit, whether or not you use our services, although if you publish any of the material, we would be grateful if you let us know and give us the credit. Some of the information is duplicated in some of the documents, so just keep what you need and delete the rest.
NOTE: We have attempted in these PDF files to provide the best available knowledge on wrought ironwork and restoration. Be patient with the large documents they do all work, just take a break for a minute whilst the download completes.
