Our new exhibition, Metal: The Wonder Material is currently open in the Craft Gallery on the 1st Floor of the museum. The exhibition uses some of the key properties of metals, both the common and the more unusual, as a lens through which to view some of the interesting and varied ways that humans have made use of this versatile material.
The Museum’s collections are full of items made from, or incorporating, metal. These range from everyday objects such as iron cooking pots and sets of keys, through to artworks, beautiful jewellery, and deadly weaponry. Humans have learned to use the incredible versatility and different properties of metals to create tools, engineer structures, and travel the world.
Humans have been using, working, and shaping metals for millennia. The importance of metal to human culture is demonstrated by the fact that certain periods of history are named after metals; the Bronze Age (2200–800BC) and the Iron Age (800BC–43AD).
Archaeologists believe that humans began to shape gold, even without the use of heat, to make decorative items as early as the Neolithic period (4000–2200BC). Gold is a very soft metal, and can be found in naturally occurring nuggets. It is sufficiently soft that simple tools made from bone, stone, and wood could be used to shape it. Also, due to its low melting point, gold can be easily melted and cast into various shapes and designs.
Although simple to work, gold is a rare material and therefore anything made from it is very valuable. Some of the earliest metal objects, dating to c.4500BC, were discovered by archaeologists at the Varna Necropolis in Bulgaria. These beautiful pieces of jewellery and personal adornments are made from gold and, due to its rarity, must have belonged to someone extremely powerful or wealthy.
Copper and tin are two of the most abundant metals in their natural ore form, and have therefore have been more commonly used than gold. They also have a low oxidation potential, meaning they are fairly easy to extract from their ores. It is thought that as early as 6500BC humans were mining and smelting (heating to extract) copper and tin in southern Asia.
Whilst copper and tin are harder than gold, they are still too soft to be used to make sharp-edged tools and weaponry. Sharp edges and sharp points are, as we know from our daily lives, essential tools. We use them to prepare and eat food, to make clothing, to groom our bodies, to build houses, to fell trees, to extract coal and gas from the ground, and to engineer the world around us. Even early humans used wood, bone, and stone to make sharp tools for hunting, building, and protection.
A major improvement in metalworking technology, and our ability to make sharp tools, came when the process of annealing, or heat treating, copper was discovered. Annealing reorders the structure of the metal by raising its temperature, followed by a slow cooling. This reordering reduces the number of weak spots in the metal and makes it more malleable and easy to shape without heat, as well as making it stronger when it is shaped and worked.
Although the exact time and method are still unknown, at some point metalworkers discovered that they could mix melted copper with tin to make a new material that was harder, stronger, and could be shaped into a sharp edge; bronze. The development of this new alloy was a major step in human technological advancement. The Bronze Age (2200–800BC) saw huge global changes, including the rise of major civilisations around the Mediterranean Sea, increased social complexity, and an enormous increase in long distance trade. It is thought that the Bronze Age arrived in Britain with the Beaker people, who came from mainland Europe, in c.2000BC. The Beaker people are so named because of the decorative “bell beaker” shaped pottery that they produced. Many Beaker burials are accompanied by metal grave goods such as jewellery and ornaments.
Another key metal in the story of modern humans is iron. Iron has a higher melting point and greater oxidation potential than gold, copper or tin, and is therefore harder to extract from its ore. As humans began to be able to build more efficient fires and furnaces that could reach sufficiently high temperatures, iron could be smelted. Once the smelting of iron became widespread it was quickly recognised as an important metal for the production of tools and weapons due its strength, hardness, and durability.
The Iron Age came to Britain in c.800BC and lasted until the arrival of the Romans in 43AD. It is so called as it is the period when the dominant tool-making material was iron. Humans had been exploiting iron before this period, but during the Iron Age people began to choose iron over previously favoured metals such as bronze. There were major technological advancements during the Iron Age, including the development of strong metal-tipped ploughshares and heavy duty agricultural tools that allowed farmers to plant crops even in dense and waterlogged soils. These advancements in agricultural technology saw the introduction of new crops, as well as more efficient production of native plants. During the Iron Age, the population of Britain increased significantly. This is likely to have been due in large part to more efficient farming and food production that came about as a result of using iron tools.
One of the major limiting factors in the use of iron is its propensity to corrode, or rust. Steel, an alloy of iron and carbon, is an extremely useful material due to its greater resistance to rust, its hardness, strength, and its flexibility. Steel tools and weapons proved to be even more effective than iron, and Noric steel was used by the Romans in their weaponry and armour. The military success and cultural dominance of the Roman Empire is likely to have been influenced by the skill of Roman steel smiths. Different types of steel were developed and used from c.1880BC onwards across India, China, Japan, East Africa, and Europe. Smiths in China and Japan were particularly famed for their skill in producing incredibly sharp and beautiful swords, using techniques that are passed on to this day.
As time moved on, humans across the world were able to process steel in new and extremely useful ways. The use of coke (a cleaner form of carbon fuel), rather than coal or wood, allowed iron to be smelted more efficiently and therefore metalworkers and smiths could more carefully control the amount of carbon introduced to the steel. This allowed them complete control over the hardness and flexibility of the metal. The properties of steel can also be affected by different methods of heat treatment. Tempering steel allows it to be strong, but still slightly flexible; by heating the steel, quenching it in water or oil, and then reheating it, the metal becomes harder and less brittle.
Metal, and metalworking technology, was central to the Industrial Revolution of the late 18th and early 19th centuries. The strength, high melting point, and malleability of steel make it a perfect material for creating largescale equipment that needs to withstand high pressures and temperatures. A key industry in which this strength was exploited was the railways. Railway tracks needed to withstand huge pressures and stresses, and therefore the engineers who worked on the early tracks used high quality steel. These steel railway tracks, and the steel-bodied locomotives that travelled on them, spread rapidly across Britain in the 19th century making it easier and cheaper to transport goods. As railway lines spread throughout Britain, the landscape changed dramatically and industrial centres expanded rapidly. Better transport links, both within Britain and internationally, changed trading and exports forever and the British economy became closely linked with the Industrial Revolution.
Many metals, and in particular steel, were also essential in the development of steam engines. Prior to the advent of the steam engine there were limited sources of power for industrial technology. The machinery used in mills, mines, and other heavy industries relied upon traditional methods such as watermills, windmills, and horsepower. As steam technology developed and improved, these efficient engines became ubiquitous in mills and mines across the country.
In the modern world we use metal in almost every aspect of our lives. Metal is in the cars we drive, the jewellery we wear, the pots we cook with, through to the electronics we use every minute of every day. Without conductive metals such as copper, the wiring, circuitry, and batteries of our phones, tablets, laptops, and desktop computers would not function. We also use metals to heal, as well as to harm. Medical equipment, such as syringes, scalpels, and diagnostic devices, are made using metals. Equally, the armour, weaponry, and vehicles used in conflicts around the world rely upon metals. For good, as well as for ill, these versatile materials have allowed humans throughout history to shape the world around them.