Black or mild steel is one of the most commonly used metals in the world and the primary material of the modern Blacksmith. It has a higher carbon content than wrought iron making it stronger, but also less malleable. It is more prone to corrosion than wrought iron, therefore is often galvanized to protect it from weathering. Because steel doesn’t have the grainy, fibrous structure of wrought iron it is more difficult to weld under the hammer. However, it is easy to weld with modern electric welding techniques. Steel is an inexpensive material and readily available in a wide variety of stock sizes.
Bright steel is improved mild steel which is free from mill scale and has been cold formed. The sections produced are very precise and even with square sharp corners. This material is often used by machinists. In decorative metalwork it can give a very sharp looking object and is useful when precise meeting of parts is required.
An historic metal and the traditional material of the Blacksmith. It’s a tough ductile and fibrous material, which is more malleable and resistant to corrosion than steel. It is very strong in both tension and compression and can be readily welded under the hammer. Today, wrought iron is mainly used in restoration and special projects where like for like materials are required and its high cost is warranted. Wrought Iron comes in several varieties, namely charcoal and puddled iron which take their names from their production methods.
Pure Iron appears relatively new to us today but was actually around in Roman times and probably earlier. It is at least 99.8% pure and is the closest to the best quality charcoal wrought iron produced in the 18th and 19th centuries, which many of our restoration projects are made from. Pure Iron is readily available and far cheaper to produce than Wrought Iron. It is an ideal material to be used in the restoration of historic metal work as it mimics many of its weather resistant qualities and malleability. It also will not de-laminate and jack apart as Wrought Iron will sometimes do.
Cast iron cannot be forged. It is a form of iron which is poured molten into moulds. It requires the associated process of pattern making to form the desired shapes which can increase initial costs, but it is a cheap way of mass producing repeat items. It is available in many varieties, most commonly grey iron or the more malleable SG iron. Cast Iron has better heat and corrosion resistance than steel and is incredibly strong in compression. It is however, more prone to fracturing and very difficult to weld.
Aluminium is the most abundant metal on Earth. It has a relatively soft ductile nature is 1/3 lighter and dense than steel. It can easily be machined, Cast, drawn and welded. It can be used as decorative metalwork where weight can be an issue. It can be easily fabricated and can have good corrosion resistance due to a thin layer of aluminium oxide that forms on the surface. Aluminium sections for fabrication are very precise and have exact square edges useful for precise constructions. The waste can be totally recycled.
Copper is a pure metal and the first metal discovered by humans who smelted it from its ore. Copper is very ductile and a great thermal transmitter and is commonly used in electrical distribution. It was the first metal to be cast into an object and is a pink to reddish brown colour when freshly exposed. Exposure to light and moisture tarnishes the colour and colours then can vary from green through blue and is often used as an architectural adornment. The statue of liberty being a great example of copper being used on a structure.
Brass is an alloy similar to Bronze but with more Zinc as opposed to Tin. The colour and properties of Brass can vary with the ratio of copper to Tin. Brass is more malleable than Bronze and can even be forged. When cast it can be made harder or softer by varying the amount of Zinc added. Brass is an attractive gold colour when polished which can be protected with either wax or lacquers. Because of the varying properties of the alloy it can sometimes be difficult to match 2 separate pieces of brass in colour.
Brass has excellent anti corrosion qualities and is often used in marine environments. The copper in Brass makes it anti germicidal and suitable for handles on doorways.
Bronze is an alloy consisting mainly of Copper with a mix of approximately 12% Tin. It can often have other properties such as Aluminium, Zinc, Manganese and Nickel.
These additions help produce a harder, stiffer and more ductile material which can be cast and machined. Used in the metalwork industry for casting objects as sculpture or sections for doorways, windows and grilles. The bronze material can be patinated to many colours ranging from the coppery red, green verdigris yellow and brown. This is achieved with various chemicals and waxes
Stainless steel does not readily corrode, rust or stain with water as ordinary steel does. Developed in the late 1920’s and starting to become popular in the 30’s Stainless Steel now has many new grades to improve its anti-corrosive properties. It is not fully corrosion resistant and certain grades should be considered for the project it is to be used in. It is an alloy and has a minimum of 10.5% chromium content by mass.
Stainless steel can be polished to a high degree and is useful in metalwork restoration if used where high oxidisation occurs. Sometimes used to replace stubs into stonework to avoid potential Jacking problems as with Wrought Iron.