Brass, steel, aluminium and iron to name the most common metals for keys but also the exotic ones, nickel silver and zama which in the latter case is not the last battle of the second Punic war, but an alloy of zinc, aluminium and copper with traces of iron and nickel.
And nickel silver? At times it can be useful to produce eating utensils because it is an alloy (which arrived in Europe from China in the 17th century) with an appearance that is very similar to silver and for which reason it is used in the production of cutlery as well as for keys for complex and top-of-the-range locks, given its beautiful appearance and good resistance.
So what is the real reason for this wide variety of materials for keys? Is there a reason for this differentiation? Or is it just a metallurgical habit? A lot has changed since the days when only wrought iron was used. Historically, brass and bronze offered a further nobility to this field, often laden with symbols. Today, there are more practical considerations to bear in mind, such as cost and workability. However different countries offer different solutions to this problem.
Steel costs much less than brass: its hardness makes it slower to work, allowing just the one worker to follow three machines at a time, while brass, which is more malleable, requires attention that increases the cost. Thus, in Germany and Spain steel is preferred but in America, Australia and New Zealand, a preference is given to brass. In Italy the decision is well considered: to the north brass is used while in the south it’s steel. In Greece, unfortunately, the change in material with a preference for steel is explained by the pressing economic crisis affecting the country.
Technically, the difference between the two materials can be seen at the time of cutting. Steel is usually avoided when working with dimple keys, choosing instead brass or nickel silver to prolong the life of the cutter.
This leads on to the fact that the type of machining strongly affects the choice of material. Apart from cast iron and zama, which only represent about 1% of the production as they are inferior materials, double bit keys must be made from brass, the Cadorine ones only from iron, while for cold pressed keys, brass or iron are used and for security and dimple keys, brass or nickel silver.
And aluminium? Aluminium is good because it can be coloured and here we enter the world of aesthetics which has been very important especially since the ’90s but also from a practical perspective given the need to distinguish at a glance one key from another. nickel silver generally stays the same colour, while brass has allowed the development of “Fancy” keys, rich in images and colours.
In addition to coining, which can be done on all materials, the other important key personalisation techniques are nickel plating which makes it shiny, basic polishing that has limited durability and blackens over time and fine polishing with its wonderful effects on colour and shine. The economics also come back into play here because obviously these processes also have very differing costs.
Finally, we are going to consider the main purpose of the key: security. Well, from this point of view, the choice of material is completely irrelevant . Resistance does not present significant differences, influenced more by encryption that, if very close to the key stop, increases the risk of breakage.
There are therefore many considerations in the choice of material: economic, technical and aesthetic but also traditions and customs reinforced by age-old practices that make the key something that is truly special.