Wood

The term “Stone Age” suggests that humans in distant memory primarily worked on rocks to master their lives. However, wood used to be a major material for constructive work as well. The oldest discovered wooden object that had been worked on is the fragment of a polished board from a Paleolithic excavation site in Israel that’s estimated to be about 780,000 years old. Even as far back as in the Stone Age, humans had tools such as simple drills, scrapers, axes, hatches, and cleavers, or splitters. The first saw-like tools were serrated hand-axes for cutting thin branches perpendicular to the fiber. Sawing as we know it today was only possible with metallic saw blades. The oldest examples of metallic saws were found in Egypt: small fragments of bronze saws with fine and coarse toothing. The first known mechanical sawmill in the 3rd century was a Roman water-powered stone saw mill in today’s Turkey in which a rotary motion was translated into a linear motion by means of a crankshaft and connecting rod. A similar principle was used in the Venetian saw featuring a single vertically cutting saw blade, driven by a slow-moving water wheel – invented, among others, by Renaissance man Leonardo da Vinci at the beginning of the 16th century. Finally, the industrial revolution put the power of steam also into saw mills. It helped achieve the breakthrough of the multiple-blade saw that was able to simultaneously cut various board thicknesses. However, the new design was struggling at first due to fears that the new, more powerful machines might cause ruin for the small saw mills. In the end, though, technological progress prevailed. Today’s industrial saw mills are high-tech lines with state-of-the-art digital measuring and control technology enabling high-speed work on large quantities of lumber. And wood waste can now be a sustainable alternative to the plastic materials typically used in 3D printing. At Chalmers University of Technology in Sweden, researchers have developed a method in which sawdust enclosed in an organic epoxy resin can be recycled for additive manufacturing.

Since the beginning of the 13th century, water-powered saw mills were spreading with varying technologies. The challenge was to convert the rotary motion of the water-wheel into the thrusting motion of the saw. Modern industrial saw mills are automated and digital high-tech lines.

Plant fibers

It all started out with twigs. Even Paleolithic humans would plait them to create a variety of utensils. Driven by the need for more flexible materials, techniques emerged enabling plant fibers and hairs to be processed into long threads, which marked the invention of spinning. Those fibers could be joined together in various ways. That led to the technique of weaving in which, unlike in plaiting or braiding, two threads are interlaced at right angles. Over time, people developed designs that would facilitate their work. In the case of the warp-weighted loom, a bundle of warp threads was vertically bound into a near-vertically standing loom. At the bottom, the threads were weighted with stones to keep them taut. To weave the weft between the longitudinal threads, the weavers would walk back and forth in front of the loom. Egyptian murals dating to around 2000 BC show flat looms as well. Despite the simplicity of these technical tools (primarily) women would produce very delicate fabrics that can hardly be created anymore on today’s computer-controlled weaving machines. That’s why weaving is described as a divine activity in ancient mythology. Across the centuries, the spinning and weaving techniques were developed further. Initial treadle looms enabled raising and lowering of the wefts so that the warp could be threaded through it faster. Approximately in the 13th century, the spinning wheel was invented for more effective yarn production because the yarn produced from flax or wool was a scarce material due to the labor-intensive spinning process. Only the novel spinning machines invented in the 18th century made cotton, a material that due to its short fibers entailed a slow spinning process, affordable for most people. The traditional weaver’s trade was now struggling because the beginning of the industrial revolution deprived it of its economic base. In the 20th century, textile production saw another revolution due to the development of synthetic fibers. In 1925, Hermann Staudinger, a German chemist, decoded the blueprint of natural fibers. That insight enabled an imitation in the laboratory. A few years later, the world-famous nylons hit the market. Currently, sewing robots, called sewbots, shape textile production. In the U.S. state of Arkansas, for example, a Chinese company has opened a factory with 330 robots where one sewbot equipped with sensors and cameras produces around 1,100 T-shirts in an eight-hour day. During the same time, ten people in a normal production line would produce about 700 shirts.

Obviously, women’s work in a factory in Lancashire, in the UK: cotton fibers are spun into yarn at a cotton mill. In today’s textile factories, you hardly ever see people anymore.

Steel

Worldwide, there are more than 2,500 standardized grades of steel – a material without which our world is no longer conceivable. Steel is defined as an iron-carbon alloy with a maximum carbon mass fraction of two percent. Alloys with higher carbon content are called cast iron and unlike steel cannot be plastically shaped in rolling mills. To get to the heart of the matter: Who exactly invented steel and when cannot be pinpointed. It’s a fact that the most important ingredient of all steel grades is raw iron that emerges from the smelting of iron ores. Liquid raw iron is produced in blast furnaces by extracting oxygen from it by means of carbon.

Allegedly as early as in the 13th century BC, blacksmiths discovered that the residual coal in their furnaces caused iron to become harder and more durable. In ancient India (6th century BC) artisans would use fireproof containers (crucibles) to smelt wrought iron with charcoal to produce Wootz steel – a material that due to its sharpness and hardness is still admired today. From the 14th century onward, layers of charcoal and iron ore were stacked on top of each other in smelting furnaces with temperatures between 800 and 900 degrees centigrade (1,470 to 1,650 degrees Fahrenheit). It marked the birth of bloom, a pasty mass of metal with slag inclusions. To remove the slag, the metal was forged.

The first blast furnaces evolved from the old smelting furnaces when these became increasingly taller and were equipped with more powerful fans. For the first time, liquid iron was produced instead of bloom – marking the transition to modern steel production as we know it today. At the beginning of the 18th century, coke was massively used for smelting iron ore. It replaced wood and charcoal, which became scarcer and scarcer. While as late as in the 17th century four metric tons (4.4 short tons) of charcoal were needed to produce one metric ton (1.1 short tons) of raw iron, today, the same amount of raw iron requires less than half a metric ton of coke (0.55 short tons). The invention of the Bessemer process by the British inventor Henry Bessemer in the 1850s made mass production increasingly simple, economic, and cost-efficient. Previously, workers had to remove the unusable substances from the molten steel by stirring it and now a machine operating with compressed air performed the strenuous job of stirring. The oxygen contained in the air burned the carbon and other undesirable incidental elements. In 1850, a blast furnace worker on average would produce eight metric tons (8.8 short tons) of raw iron. Within the space of 20 years, the production quantity increased tenfold. In 1912, scientists of the German Krupp Group accidentally discovered that alloying of iron, chrome, and nickel creates corrosion-proof steel, marking the invention of stainless steel. Today, the subject of sustainability – steel is already the most frequently recycled material worldwide – plays a major role. The motion technology company Schaeffler is going to switch to climate-neutral production paths as well, the keyword being green steel. Starting in 2025, ­Schaeffler will purchase 100,000 metric tons (110,000 short tons) of steel produced in a nearly CO₂-free process from Swedish startup H2 Green Steel. The reason is that every year Schaeffler consumes flat steel with a weight equating to that of 92 Eiffel Towers. Compared to conventionally produced steel, the CO₂ emissions of the green steel purchased from H2 Green Steel decrease by as much as 95 percent due to the use of hydrogen instead of coke.

When steel was liquefied it became a mass product. According to the umbrella organization Worldsteel around 944 million metric tons (1,041 million short tons) of raw steel were produced in the first half of 2023 worldwide – one percent less than in the same period the year before.

Sand

Understanding the importance of the multi-talented material sand requires some reflection on the question of what our lives would be like if sand disappeared from them. Hardly anything would work in an average household. Sand is contained in countertops, kitchen fronts, in toothpaste, shower gel, in plastics, color pigments, and even in shredded cheese as an anticaking agent. Sand is indispensable – particularly in the construction sector. In just three years, from 2011 to 2013, China is supposed to have used as much sand in construction projects as the United States in 100 years, from 1900 to 2000. On a global scale, humans use around 50 billion metric tons (55 billion short tons) of sand per year, typically in the form of concrete and cement. The valuable grainy raw material has a very long multi-faceted history. As far back as around 15 BC, Emperor Drusus built the Roman road Via Claudia Augusta on sand. Around 2,000 years ago, the Romans developed “opus caementitium” concrete – an artificial stone that thanks to mixing in volcanic ash was enormously robust. They used it to erect buildings by hand without the help of high-tech machines. Some of them still exist today. The most important types of sand include quartz sands. As early as in the 7th century, the Chinese knew how to make white porcelain from quartz, kaolin, and feldspar using specialty mills and casting molds. The history of glass is even older. Long before the birth of Christ, people were able to produce glass from quartz by applying enormous heat. Glass contains around 70 percent quartz sand. The invention of the glassmaker’s pipe in Syria in 200 BC marked a technical revolution. It enabled the creation of sophisticated shapes. Industrially produced glass made its way into nearly all areas of daily life. Computers, smartphones, and TV sets would be inconceivable without sand as well. What’s more, the silicon contained in quartz sands can convert alternating electric current into direct current. Today’s microelectronics would hardly be thinkable without that property. But quartz has even more abilities. It’s literally a seamless material. Once compacted, it provides an ideal “frame” for shaping cast-iron workpieces. This manufacturing technique is still used today particularly for large specialty workpieces. Specialty filtering systems using quartz sands for purifying drinking water can be found everywhere today. There’s no need for humanity to worry about a lack of eco-friendly further developments. In Canada, architects have used recycled glass instead of carbon-intensive cement as a binding agent for the construction of two concrete bridges which reduced the emission of greenhouse gases by 40 metric tons (44 short tons).

Glassmakers typically settled in areas where they could find enough firewood for their smelting furnaces. When all the wood had been cut, they’d move on. The big advantage of glass is that 100% of it is recyclable and can be reprocessed into new glass packaging material as often as needed.

Light

For a very, very long time, the Sun was the only relevant light source on this planet. Until about 300,000 years ago, when prehistoric humans discovered fire as a source of heat and light. But it wasn’t until 1879 that Edison’s incandescent lamp marked the beginning of electric lighting. Candles and petroleum lamps were still in daily use in Europe up until the 20th century. In research settings, light as a non-substantial material is used for a wide variety of purposes. German researchers, for instance, supply micro-algae with lots of light from which the plankton cells generate energy by means of photosynthesis. In return, the algae provide valuable ingredients for cosmetics, pharmaceuticals, and foods. Once all the valuable substances have been used up the residual biomass is processed into biogas. Light as a material has a wide range of applications. For instance, the nuisance of having to fill one’s mouth with an unpleasant paste to obtain dental impressions might end soon. A novel scanner developed in Jena at the Fraunhofer Institute for Applied Optics and Precision Engineering can measure the shape of a set of teeth with accuracy down to a few micro­meters. To do so, the scanner projects extremely delicate light strips onto the tooth surface. The strips place themselves exactly over the enamel and measure the tooth contours. With these data, a machine can precisely mill dental prostheses. Other applications for efficiently using light as a material via novel solar cells are being investigated at the Fraunhofer Institute for Solar Energy Systems in Freiburg. In the case of organic solar cells, for instance, flexible semiconductor material replaces the stiff silicon plates of conventional modules. Soft cells like these can be sewn into jackets and pants to generate electricity on the go. The researchers have applied pigments to other photovoltaic components. Installed on windows, they supply electricity and at the same time provide sun protection.