===== MATERIALS ===== For most of its existence, humanity has used materials taken from the environment and only lightly processed: wood, grass, earth, stone, hide, and bone shaped into useful objects. ==== STONE AND EARTH ==== The most durable items from antiquity, and therefore those about which we know the most, were made from inorganic materials, starting with stone and earth. === Flaked Stone Tools === Produced at least 2.5 million years ago, the oldest surviving tools are made from flaked or chipped stone. Materials such as flint, chalcedony, chert, and obsidian have a glassy internal structure. When a mass is struck, the shock of the impact propagates in a predictable wave and cracks the stone along the wave’s edge. The simplest stone tools were made by striking a stone with a hammer – typically a convenient pebble – to knock off a single flake with a sharp edge. Flake tools can be extremely sharp, but their edges wear down after a few cuts, even on something soft such as cloth fibers. More durable tools were shaped by striking multiple flakes from a core. The working edge was actually a series of small edges produced by removing the waste flakes, giving a serrated look. Core tools aren’t as sharp as flakes, but can be “resharpened” by knocking off more flakes. By the Neolithic, pressure-flaking was developed: a punch made of horn or bone was pressed against a core’s edge to produce minuscule flakes. Some TL1 societies, notably the more sophisticated civilizations of Mesoamerica, could produce pressure-flaked blades five or six inches long and less than a quarter-inch thick, each with a razor-sharp edge. Though larger flakes and well-shaped cores could be used by themselves, many stone tools were incorporated into composite items; e.g., arrow and spear heads were attached to wooden shafts. As stone tools become more sophisticated, very small stone parts – microliths – came into use. Tiny flakes were set in wood or bone handles to yield sickles, or added to spears and arrows as barbs. === Ground Stone Tools === Ground stone axes were made from extremely hard minerals such as basalt and jadeite. Stones were given a rectangular or oval shape by pecking and rubbing against other stones, and then one end was polished down to an edge. This wasn’t particularly sharp – perhaps comparable to a dull slothead screwdriver. It was more durable than a chipped stone tool, though! Fixed to a wooden haft, it could fell trees or break bones. When the edge dulled from wear, more grinding could resharpen it. Softer stones such as limestone and pumice could be shaped more quickly, yielding tools for grinding grain and other dried foods. Given their great weight, ground stone tools are usually associated with sedentary cultures. Nomadic hunter-gatherers might carry a ground stone axe or mace, but a heavy bowl or grinding stone is too inconvenient to lug around. === Cut Stone === By TL1, sedentary societies began to make use of a different range of stones. Blocks of stone were cut by a number of methods, most often direct chiseling, sawing, abrading with sand or thick wire, and drilling. Although stone was still relatively expensive, entire stone buildings became affordable, and stone quickly became the material of choice for palaces, fortifications, and sacred buildings. Gypsum was one of the first stones deliberately shaped for building; from the Bronze Age through the Middle Ages, civilizations around the Mediterranean used it as a structural or decorative material. Sandstone also saw use, notably in the American Southwest. Slate – which breaks easily into flat plates – was employed occasionally for construction and frequently for roofing. Limestone, though, became the overwhelmingly popular material, used for everything from the Pyramids to Gothic cathedrals. It was common and, while harder than gypsum and sandstone, balanced durability and workability. Even harder stones, notably marble and to a lesser extent granite and basalt, were on occasion used for particularly fine masonry, but the cost was usually prohibitive. Stone was cut for tools and portable decorations, too. The usual building stones were shaped into both fine sculptures and sophisticated grindstones that more efficiently turned grain into flour. The Vikings made extensive use of soapstone, which was soft enough to carve with iron knives. === Precious Stones === Tiny quantities of semiprecious stones were used for ornamentation far into antiquity, but they weren’t seriously mined or worked until the sixth millennium B.C. in Egypt and China. Bronze Age civilizations used turquoise, jade, lapis lazuli, jet, and varieties of quartz. These stones were soft enough to carve into seals and tiny figurines, or into very thin pieces for inlay. Precious stones were discovered later. Emeralds were mined in Egypt by the early second millennium B.C.; sapphires and rubies, in southern Asia in the first millennium B.C.; and diamonds, in south central India around the fourth century B.C. Most of these stones came from a handful of sources. For example, Egypt remained the Old World’s sole source of emeralds well into the Middle Ages, while all ancient lapis lazuli came from northeastern Afghanistan. Note that such stones were used almost entirely for decoration at TL0-4. Watch movements using jeweled bearings were invented early in the 18th century (very late TL4). === Earthenware and Brick === Pottery first appeared around 12,000 B.C., in Japan. It’s made of a material common everywhere: dirt. Wet clay – possibly containing an admixture of sizing (sand, shell, or ground waste pottery), which stiffens the clay and prevents slumping during firing – may be shaped, left to dry, and baked to at least 1,080°F. The clay particles fuse into chemically stable earthenware pottery. Indefinitely reusable and resistant to moisture and vermin, pottery is excellent for long-term storage. However, pottery vessels are also brittle and heavy. Containers light enough to be easily portable are fragile, while those thick enough to withstand jostling are too heavy to carry casually. Thus, they are the storage of choice only for sedentary peoples. While invented by hunter-gatherers, pottery didn’t really take off until the rise of agriculture. Formed into blocks rather than vessels, pottery becomes brick. Clay for bricks was sometimes mixed with straw or pierced with holes to lighten the final product. Brick is far more durable than any material short of stone, but also less expensive than stone. === High-Fired Ceramics === Fired to 1,700°F, ceramics start to vitrify, or become glassy, throughout. The resulting materials, sometimes called “stoneware,” are tougher and more waterproof than earthenware, but still slightly porous. However, stoneware needs more than just heat. Many clays don’t vitrify at such temperatures – they melt! Stoneware requires more careful clay processing and a more limited range of sizing materials than earthenware. The first stoneware appeared around 3000 B.C., in Mesopotamia. Fully vitrified stoneware – which is completely waterproof – dates to the first millennium A.D., in China. It appeared even later in Europe. Porcelain, first produced in China late in the first millennium A.D., is a particularly prized high-fired ceramic; see The Race for Porcelain (below). It’s made from petuntse and kaolinite – not particularly common minerals – and the resulting clay is difficult to work. When fired at 2,200°F, however, it completely vitrifies, becoming both waterproof and slightly translucent. === The Race for Porcelain === The story of porcelain in Europe is a low-tech tale of scientific research and industrial espionage. Chinese porcelain commanded astronomical prices in Renaissance Europe. However, its production was a mystery to European potters. Powerful patrons, seeking money and prestige, sponsored workshops attempting to re-create Chinese ceramics. Experimentation produced useful near-misses such as “soft” porcelain (which mixes glass with white clay) and bone china (which contains large quantities of bone ash), but the secret remained elusive for centuries. In 1709, Johann Böttger, an alchemist working for the Elector of Saxony, finally produced a hard, translucent ceramic that could be decorated with glazes resembling those used in China. The formula for porcelain was a jealously but imperfectly guarded secret for years thereafter. Nevertheless, the industrial spies who uncovered Böttger’s secret kept it hidden themselves, and Europe had only three factories producing porcelain until the middle of the 18th century. === Glass === Historical glass was made of silica, which forms the body of the glass; a flux (usually sodium carbonate), which lowers silica’s melting point from above 4,000°F to just over 2,000°F; and lime, which controls the water solubility of sodium carbonate and keeps the glass waterproof. Metallic salts were sometimes added for color. Production methods placed significant limits on glass’ form and quality. //Core Formation// (TL1). In this process, developed around 3500 B.C., raw materials were combined and sometimes layered to produce multiple colors, surrounded by fuel, and completely covered to retain heat. This produced a biscuit-shaped lump of colorful but mostly opaque glass. Some shaping was eventually possible, with cores being shaped around earthen forms that were scraped out later. //Glassblowing// (TL2). In the first century A.D., improved furnace designs allowed glassmakers to use open furnaces and inflate lumps of molten glass on the ends of metal tubes, producing attractive thin-walled vessels. //Optical Glass// (TL3). By the 11th century in the Near East and 12th century in Venice, glassblowers developed truly clear and colorless glass suitable for corrective lenses and transparent windows. They used a potassium-rich flux and naturally pure sand without color-causing metallic salts. Glass mirrors backed with silver foil began to compete with heavier, more expensive mirrors made from solid metal plate. However, metal mirrors remained in use for some purposes. At TL4, Isaac Newton invented an alloy for telescope mirrors (see GURPS Low-Tech Companion 1), called speculum metal: a tin-heavy bronze with arsenic added to remove the red-orange color. === Mortars and Mineral Adhesives === A mortar is a mixture of an adhesive and sand, extending the adhesive and giving it greater strength once set. //Mud// (TL0). A mixture of dirt and water is extremely vulnerable to water, but it’s very cheap and makes a good windproof surface. Consequently, it was the material of choice for many domestic structures in dry environments. Reduce the HP of stone or brick buildings using mud mortar by 5%. //Plaster// (TL1). Plaster, made from burnt gypsum, was used as early as 7000 B.C. The most common application was smooth wall surfaces, but it could be poured into molds to produce inexpensive sculpted decoration. Plaster is a good background for painting, but the artist must work quickly, while it’s still wet! Reduce the HP of stone or brick buildings using plaster-based mortar by 2%. //Lime// (TL1). Serious structural adhesives are based on lime, which was in use by 4000 B.C. Lime is produced by heating limestone to 1,500°F, which turns it into a powder. //Quicklime//, the initial product of such heating, is a caustic powder (Lime Powder). It’s also unstable – over time, it reabsorbs atmospheric carbon dioxide and reverts to limestone. For safe storage and handling, it’s mixed with a little water to produce “slaked lime.” Adding more water gives a paste that sets into a solid form. Mixed with salt and a lot of water, quicklime becomes whitewash: a rough, thick white paint used from at least late TL2. Lime has also been used as a bleaching agent and a cleanser. //Concrete// (TL2). Concrete is a mixture of lime mortar, pozzolana (a volcanic ash), sand, and stones. It’s waterproof and even sets underwater. This mixture was first used by the Greeks as early as 500 B.C. Roman masons realized that it could be poured into wooden forms and set strongly enough to serve as a structural material in its own right. Inferior concretes – not as strong, but still water-resistant – could be made with ground pottery in place of pozzolana. Both fell into disuse by the Middle Ages, perhaps because they required specialized knowledge to compose and use. ==== METALS ==== Use of stone- and earth-based materials eventually led people to exploit metals. Few metals are available in a native (naturally pure) state; gold and copper are the most common, but even those are extremely rare. Serious metal use requires that ores be smelted: heated to a temperature where the metal separates from the elements with which it has combined in the ore. The discovery of smelting unlocked large quantities of metal and made possible the Bronze and Iron Ages. === Copper, Bronze, and Brass === Copper (which melts at 1,984°F) was the first tool metal, used by 5000 B.C. in the Near East. It makes tolerably good tools, but alloying it improves its workability and hardness. Several important copper alloys – comparable to iron in hardness – started to appear around 3500 B.C. in Egypt, the Near East, and north-central China. //Arsenic Bronze// (TL1). An alloy with 2% arsenic, likely produced by smelting ore that happened to contain arsenic, was the first popular copper alloy and the most widespread into the third millennium B.C. Arsenic is toxic, however, and may have left smiths with long-term nerve damage. //Tin Bronze// (TL1). The preferred copper alloy (“bronze” almost always refers to tin bronze) contained 5% to 15% tin. In addition to being nontoxic, tin bronze was easier to cast. Tin is extremely rare, though, so other alloys remained in use, and inferior low-tin bronzes were common. //Brass// (TL1). This alloy is 5% to 15% zinc. The problem with producing brass is that when zinc oxide – the primary zinc ore – is smelted, the zinc escapes as a gas. Instead of making pure zinc, smiths in the first millennium B.C. added zinc oxide to copper and heated them together, releasing the zinc into the copper. === Iron and Steel === Copper and its alloys suffered from a significant flaw: scarcity. While iron requires more work to produce, it’s many times more common in the Earth’s crust. Native meteoric iron was used in minute quantities from as early as 4000 B.C., but iron manufacture didn’t begin until around 1500 B.C., in the Near East. Iron can be smelted at 2,190°F, but it doesn’t melt until 2,800°F – far beyond the reach of furnaces until TL5. Unlike copper, then, early iron didn’t run out of the furnace into a convenient puddle. When ore was smelted, the iron was contained in a matrix of rocky slag. Smiths pounded a softened but still solid bloom of wrought iron out of this with hammers. Iron wasn’t as easy to alloy as copper, but it could be treated to incorporate carbon, turning it into steel (iron containing 0.5% to 1.5% carbon). The most widely practiced technique was to hammer a piece in a charcoal fire. Carbon from the fire infiltrated the surface, hardening it. Smiths might extend the technique by welding together thin layers of hardened and unhardened iron, or stretching and folding partially hardened iron, producing pieces that balanced wrought iron’s resilience with steel’s durable hardness. Smiths eventually developed two main methods of making steel through and through. The easier method combined finely crushed iron ore and charcoal dust in a small clay container. With sufficient heating, carbon completely infiltrated the iron, lowering its melting point to an achievable 2,100°F. The resulting metal had to be hammered extensively, but this technique – practiced through most of TL3 Asia, but unknown in Europe – produced small quantities of high-quality steel. The other method, the //blast furnace// (TL4), involved pushing lots of air through lots of charcoal in the furnace, burning it quickly and producing very high temperatures. In addition to generating tremendous heat, this increased the iron’s carbon content to 5%, pushing it past steel into very hard but brittle cast iron. Cast iron could later be cooked in an oxygen-rich atmosphere to reduce its carbon content, turning it into steel. Early smiths might use 8 lbs. of ore and 36 lbs. of charcoal to produce a pound of iron. By the beginning of TL3, a well-designed furnace could produce a pound of iron from 7 lbs. each of ore and charcoal. However, less-efficient designs – using up to twice as much charcoal – were common. Depending on the quality of the excavated ore, the total amount of charcoal (including roasting and other pre-processing) could rise to 30 times the amount of metal produced! Early furnaces produced 100 to 150 lbs. of iron at a time. By TL4, large furnaces could produce up to a ton of iron. Late-TL4 furnaces producing cast iron consumed twice as much charcoal as their wrought-iron predecessors. === Lead === Too soft for tools, lead was nevertheless important by TL2. With its malleability and low melting point (621°F), it was ideal for durable waterproof seals, roofing, and water pipes. It was also used in sling bullets (p. 74), weights for fishing nets, and clamps connecting masonry blocks, and as an ingredient in enamels and glazes. Lead ores used in antiquity were frequently associated with other metal ores, notably silver. Lead was produced as a byproduct of smelting those metals. The combined ore was heated in an oxygen-rich atmosphere to remove other metals and convert any lead ores into lead oxide gas. The lead oxide was captured in a layer of ash or sand, and then heated again in a low-oxygen atmosphere to smelt out the lead. Since lead is toxic, long exposure to its vapors could cause neurological problems for smiths who worked with it. === Mercury === In addition to fanciful alchemical work, mercury was used for ore processing. Gold, silver, copper, and zinc are mercury-soluble. Mixing them or their ores with mercury forms an alloy, or amalgam. Iron doesn’t form amalgams, and so was used for mercury flasks. At least as early as TL3, mercury was used to capture silver and gold in unrefined ores. The amalgam was heated to remove the mercury (producing a toxic gas, like lead smelting), taking less total work than conventional smelting. Mercury was obtained from cinnabar, its sulfide ore. Cinnabar was also in demand as a red pigment. Heated to 930°F in an oxygen-rich atmosphere, it naturally decomposes and releases mercury vapor. === Tin === Tin was rarely used on its own, but was in demand for bronze and pewter: a family of dull-silvery tin-heavy alloys. Pewter formulations include antimony, copper, lead, and zinc in varying proportions. Pewter was too soft for tool use but easy to work and cast (melting point around 500°F), making it a popular choice for household items starting late in the Middle Ages. Pewter served a similar function to silver, but was cheaper (though not much – tin is only slightly more common than silver) and didn’t tarnish. === Zinc === Pure zinc was produced in India by the 13th century A.D., spreading to China by the 16th. The ore was smelted into a vapor, which was directed downward into a watercooled vessel to condense into solid metal. It was occasionally used for ornaments and coins, but more often for high-zinc brass alloys. Smelting zinc directly into copper to make brass imposes a maximum zinc content of just under 30%. Brasses with higher zinc content require the addition of pure metallic zinc, and resemble gold. === Precious Metals === Tools were made from lesser metals, but economies were built on gold and silver! //Gold//: Gold melts at 1,947°F. It generally appears in a native state, and was used by 5000 B.C. Its malleability made it ideal for decorative use. Native gold might contain other metals – particularly silver – but purifying it was rarely a concern in the New World, and only became important in the Old World with the rise of coinage. //Silver//: Silver melts at 1,763°F. It typically occurs with other metals – usually lead or gold. When separating silver from gold was important, unpurified metal leaf or dust was combined with salt and heated to the melting point to combine the silver with the chlorine in the salt. The pure gold was poured off, and the remainder smelted again to recover the silver. //Platinum//: A few societies discovered minute quantities of native platinum, but most didn’t even recognize it as a metal. Spanish conquistadors discarded platinum nuggets as worthless lumps in valuable silver! Even in societies that valued it, platinum couldn’t be smelted or melted down, and was too rare to be anything but a curiosity. === Wire === Wire was first made early in TL1 by laboriously pounding metal rods into grooved anvils, or with grooved hammers. By early TL2, drawing (pulling metal through a narrow hole) was developed. Both techniques were practiced with soft metals such as gold first and iron later. Regardless of methods and materials, wire-making was expensive and time-consuming. Wire was produced mainly for decorative purposes (necklaces and chains, wrapping around a core to make a textured surface, etc.), but iron and bronze wire were cut into segments for mail links, pins, and other applications where stiffness was a virtue. Since great lengths were unwieldy, and wire broke easily during production, pieces were rarely more than a few yards long. Note that strong, flexible “piano wire” isn’t actually wire, but metal wrapped around a fiber core. It first appeared late in TL4. ==== ORGANICS ==== While surviving relics of antiquity are mainly inorganic, far more items were made from perishable but more-abundant organic materials: wood, grass, and animal parts and products. === Wood === Woods can be divided roughly into softwoods and hardwoods. Softwoods – mostly from evergreens – are less dense and therefore less durable, but easier to transport and work, and faster-growing. Denser hardwoods are preferred for most applications, but take much longer to grow. Historically, most species were found to be better for some uses than others, to the point that certain woods were important trade items. For example, in the Bronze Age, Lebanon exported cedar through the eastern Mediterranean. There are indications that hunter-gatherers deliberately cultivated forests. While trees weren’t systematically planted like fruit orchards, they were kept free of underbrush. This gave hunters better visibility and other useful plants room to grow. Where possible, foresters didn’t kill trees. By 4000 B.C., woodsmen practiced coppicing: cutting the tree close to but not at the ground. Since the roots were intact, new shoots came up far faster than from a seedling. Willow for basketry could be harvested every year, though decades might pass between harvests of slow-growing hardwoods. Under normal circumstances, it takes 2 x (square of diameter in inches)/BL minutes to fell a softwood tree using a metal axe – or double this time for hardwood. Stone axes aren’t as sharp or as well-hafted as later axes, and are far less efficient; quadruple these times when using one. Cutting lumber costs FP at the same rate as digging ordinary soil for most trees, or digging hard soil for especially dense woods such as oak or ebony (see Digging, p. B350). Depending on the tree species and its tendency to grow branches, it takes 5-10 times as long to trim it into a useful log, or up to 30 times as long to turn it into firewood. A square mile of forest can provide 1,200 to 2,600 tons of wood, although only half to two-thirds of that might be turned into logs and boards for building. Wood dries for several months after it is cut, shrinking in the process. Lumber is typically seasoned – left to dry and deform – so that it reaches a stable shape before being used. This doesn’t matter when building wooden items for short-term use (e.g., catapults during a siege), but anything made from fresh wood will warp and can even break over time. Any object made from unseasoned wood loses a point of HT every other month for six months. Each time it loses HT, roll against the new HT; failure means the item drops a step in quality (for instance, a good-quality weapon becomes cheap). On a critical failure – any failure, for a cheap-quality artifact – the object breaks and becomes useless. === Bone, Horn, and Shell === Bone, horn, and shell can be cut and carved in much the same way as wood, but are superior for some applications. Being more resistant to fraying and splintering, they’re suitable for pointed tools: awls, sewing needles, etc. They can even be turned into weapons – all can be sharpened to a point, and some shells provide a cutting edge. These materials saw heavy use in tools into the Bronze Age, when metals took over their niche. They continued to fill decorative roles, though. For instance, horn and ivory can be turned into flat plates. They’re softened with hot water or steam, cut open, and separated into layers which can be flattened, dried, and carved into combs, utensils, and shapes for inlay. Likewise, certain shells – particularly those with a pearly layer of nacre – were cut into small parts for use as inlays. === Leathers === Leather is animal hide treated to preserve both substance and flexibility. It may have been the first clothing material, and was used for containers and protective coverings. It’s windproof, water-resistant, and harder to damage than fabric. However, it’s also more difficult to repair once damaged – and while leather provides short-term protection from water, significant wetting will cause it to stiffen and crack upon drying. To make leather, hide is scraped free of flesh and hair – possibly after treatment with salt, lye, dilute lime solutions, or dung, or simply being left to age for a few days. If dried at this stage, the scraped hide becomes stiff rawhide. To remain flexible, leather needs to be tanned. Tanning extracts water from inside the cells that make up the leather, while leaving them otherwise intact. The earliest tanning material was brains, although some societies used solutions made from boiled oak or aged urine. The customary rule is that an animal has enough brains, crushed into water, to tan its own hide. The tanning solution must be rubbed or stamped well into the hide, which takes two to three hours. Finally, the hide may be lightly smoked and oiled to enhance suppleness and repel insects. Active working time for scraping and stretching might be just a few hours. However, the hide must spend considerable time soaking and drying. The entire process takes one to three weeks. === Furs === A fur is simply a hide turned into leather without damaging the hair on the outside. The fleshy side must be scraped carefully to prevent damage to hair roots, and washed to remove any oils on the hairs themselves. The tanning process has to be carried out carefully to avoid tearing out the hair. The extra effort for superior insulation was often worthwhile at TL0 – but as cheaper cloth appeared at TL1, fur production became a luxury trade. === Domestic Animals === Domestication is the process of adapting plants and animals to breed in close proximity to humans. The animal species best-suited to domestication are those that aren’t fussy about their diet and the conditions under which they reproduce, and that are amenable to living near humans. At the same time, humans have worked to create “artificial” environments – e.g., irrigated fields and safe, grassy pastures – to keep a species nearby. Dogs might have been the first domesticated species, as early as 30,000 B.C. However, domestication didn’t take off until the rise of agriculture between 9000 and 8000 B.C. Several cereal grains were first cultivated in Egypt and the Near East during that period, followed by corn and squash in Mexico by 7000 B.C., and rice in the Yangtze Valley around the same time. Humans began to cultivate an increasing number of species (e.g., almonds in the Near East, around 4100 B.C.), eventually foregoing wild species as economically significant. Adaptations for domestication were often the result of selection. For example, the earliest domesticated animals were smaller than their wild ancestors, likely because weaker animals were easier to confine! Similarly, many domesticated crops required less effort to harvest than their wild cousins, because easy-to- harvest varieties were gathered disproportionately from the wild. After initial domestication, humanity subjected suitable species to countless generations of selective breeding. For instance, horses grew steadily larger from their small, initially domesticated size. The emergence of new demands likewise influenced breeding efforts. Notably, animals were originally domesticated largely for meat, but by 3000 B.C., a range of new uses appeared in the “Secondary Products Revolution.” Animals were kept increasingly for wool, milk, and labor, and were bred for traits that supported those uses. === Fiber === Human use of fibers – probably as cordage – goes back at least to 32,000 B.C., in the form of linen fibers collected from wild plants. //Reeds// (TL0). Reeds such as flax, jute, hemp, and sisal are processed by crushing or soaking. The earliest woven fabrics yet found, dating to 7000 B.C., were made of flax. However, shoes woven from sage – somewhere between fabric and wicker – date to at least 8000 B.C. //Cotton// (TL0). Several societies had access to cotton, independently domesticated in Mesoamerica and India. It must be combed to remove tiny seeds before it can be spun. //Wool// (TL0). Wool wasn’t used extensively until the late Neolithic. Collected mostly from sheep in the Old World and llamas in the New, wool must be treated (usually boiled) to remove oils before it can be spun. Wool is expensive, as it requires that large herds of animals be maintained, but it spins easily, is an excellent insulator, and can be felted. //Silk// (TL1). Silk is made from the cocoons of several moth species. Only one – the mulberry silkworm (Bombyx mori) – could be cultivated. Others were gathered from the wild in small quantities; for example, the Greeks gathered fiber from wild moths on the island of Cos. Silk from domesticated silkworms was first produced in China in the early third millennium B.C. Despite being traded as far as Egypt, it remained a Chinese monopoly until the late first millennium B.C. Sericulture reached the Byzantine Empire by the early Middle Ages. Silk is exceptionally strong and easy to make into extremely fine thread. The fibers have a triangular cross section, giving silk an attractive iridescent quality. //Asbestos// (TL2). Besides the organic fibers known in antiquity, one mineral fiber saw use. Asbestos – mined in the Near East and India – was spun and woven, with considerable effort, into an extremely expensive fireproof fabric as early as the first century B.C. It was made into easily cleaned table linens (just throw them on the fire!) and fireproof clothing. The earliest commentators on asbestos noted damage to the lungs of those who mined it. Asbestos goods, if available, cost 100 times as much as other cloth items, and provide DR 2 vs. burning damage. //Spider Silk// (TL4). Spider silk wasn’t exploited on an industrial scale, but TL4 chemists experimented with it. The primary historical use of spider web – when it was used as all – was to dress small wounds (see Cobwebs, p. 146). However, stripped of adhesives, spider silk can be turned into thread with potentially twice the strength of silk. For spider-silk armor, see Silk (p. 104). === Rope, String, and Thread === Many fibers can be turned into cord simply by rolling them between the hands or fingers. Early yarn spinning used a spindle: a rod that held a mass of fibers on one end and the developing strand wrapped around the other. Early in TL3, the spinning wheel appeared, increasing the speed of yarn and thread production. The wheel was attached by a belt to a spindle, like one that would be used by hand. Instead of the spindle being turned slowly by hand, the wheel rotated it quickly, drawing a thread from a mass of fibers held in the spinner’s hand. By TL4, the Chinese had developed wheels that could turn up to five spindles at once. Rope production typically involved twisting long strands together, giving them a definite left- or right-turning tendency. Length was limited by the size of the laying yards that could be cleared for their manufacture. Historically, ropes longer than 200 yards were extremely rare. For greater lengths, multiple ropes were usually spliced together. All the ropes described below are 1” thick. To get thicker or thinner ropes, multiply weight, cost, and strength by the square of the diameter in inches. The thickest ropes in antiquity – connected to harnesses or capstans rather than pulled by hand – topped out at around 2.5” in diameter. Example: 10 yards of 1” hemp rope can support 2,000 lbs., cost $30, and weigh 9 lbs. A 3/8” rope of the same material can support 9/64 x 2,000 = 281 lbs., costs $4.20, and weighs 9/64 x 9 = 1.26 lbs. Rounded up, these figures are similar to those on p. B288. A 1” diameter rope is about the thickest that ordinary humans can grasp effectively. Larger individuals can grasp thicker ropes: Double diameter for every +2 SM; for odd SM, multiply by 1.5 for the extra +1. You can use a rope that’s too thick for you, but you suffer -1 per excess inch of thickness to both effective ST and applicable skills (e.g., Traps skill to set snares). The weights listed below assume stationary loads: hauling cargo, suspension bridges (see GURPS Low-Tech Companion 3), etc. For situations where the rope undergoes dynamic loads and sudden shock – e.g., towing and climbing – it can support only half as much. For instance, that rope with a maximum load of 281 lbs. will only support 140 lbs. if the user is climbing quickly... or if he falls and the rope must save him! If he climbs slowly (less than half normal climbing speed), the rope will support the full 281 lbs. //Grass// (TL0). A quick, temporary rope can be made by braiding the stems and leaves of grass or thin reeds together. A green grass rope has about 1/5 the strength of a rope made from tougher plant fibers. Supports 360 lbs. Per 10-yard length: $3, 9 lbs. //Vines/Ivy// (TL0). A thick, supple vine – or several thinner ones twisted together – can make a serviceable rope. Supports 900 lbs. Per 10-yard length: $10, 9 lbs. //Plant Fibers// (TL0). Standard rope is made from tough plant fibers like flax, papyrus, jute, and yucca. Supports 1,800 lbs. Per 10-yard length: $20, 9 lbs. //Hemp and Manila// (TL0). These plant fibers are stronger than most. Today, manila is preferred over hemp because it’s more resistant to water and salt. Supports 2,000 lbs. Per 10-yard length: $30, 9 lbs. //Animal Hair// (TL0). It’s difficult to collect enough hair to make a rope of significant length. The Romans seem to have preferred goat hair. Human hair is useful because it can be grown longer than the hair from many other mammals; cord made from women’s hair was sometimes used in catapult springs (see Mechanical Artillery, p. 78). Use the stats for rope made from plant fibers. //Braided Hide// (TL0). Rope can be made by braiding or plaiting together leather or rawhide strips. Walrus, seal, buffalo, rhinoceros, and caribou hide have all been used for this. Treat as plant fiber rope (p. 25), except that it costs three times as much and can only be manufactured in lengths of up to two yards, which must be spliced together to obtain longer segments. Hide rope is also highly susceptible to water; wet hide can handle half its normal load. These rules apply equally to dried gut, often used for bows and stringed musical instruments. //Silk// (TL1). Silk is extremely strong but loses some of that strength every time it’s processed; thus, raw silk is best for rope. Silk is highly susceptible to ultraviolet radiation and abrasion, and deteriorates quickly; it loses 10% of its strength per year (see Rope Deterioration, below). Supports 5,000 lbs. Per 10-yard length: $100, 5 lbs. == Rope Deterioration == All fibers deteriorate over time. Some are susceptible to moisture, mildew, and rotting; others, to ultraviolet radiation (present in sunlight). Most don’t like temperature extremes. Frequent use causes abrasion. Impact reduces strength even further. As a general rule, rope that’s used regularly loses 5% of its strength per year; e.g., a rope that could support 2,000 lbs. when new will support only 1,600 lbs after four years. Severe conditions – especially excessive moisture – double the deterioration rate. Conversely, rope stored in a cool, dry, dark environment loses a mere 1% per year if it doesn’t see regular use. Rope is sometimes coated with tar to protect it from weather; this doubles cost and increases weight by 10%, but halves deterioration rate. === Cloth === The earliest fabrics – and the most common ones through history – were woven. Yarn went on a loom in a set of taut parallel strands (the warp). The weaver passed a separate strand of yarn (the weft) back and forth between warp threads at a right angle. The simplest looms (late TL0) required the weaver to weave the weft back and forth between the warp threads individually; later designs (TL1, although inexpensive older designs persisted into TL2) separated warp threads into alternating groups with a V-shaped passage – the shed – between them. The loom could be operated to switch the upper and lower threads of the shed, locking the previous weft thread in place and preparing the way for the next. Knitting uses a more complex technique but simpler tools. It appeared in northern Europe as early as 6500 B.C. (late TL0), with a single-needle technique producing tubes of yarn. True knitting, using two needles, didn’t appear until around 1000 A.D. (TL3). Early knit pieces were also tubes, almost always used for stockings, although they might be cut open to form flat pieces. Flat knit fabrics didn’t appear until the 1500s (TL4). Finally, cloth was created by felting – possibly as early as TL2. Instead of being spun into threads for weaving, wool fibers were wetted, rubbed against one another to fray the surfaces, and pressed together. Felt is relatively dense and stiff, but extremely resistant to unraveling. Some textiles were treated with a hybrid process. Woolen fabric, once woven, was scrubbed with urine (TL2) or fuller’s earth (a type of clay; TL3) to remove residual oils, and then pounded in water to mat fibers together into a hard-wearing form like felt. This process, fulling, was an important medieval industry. === Wicker and Thatch === Grass, reeds, wood strips, pine needles, and leaves have all been used to make light, inexpensive wicker baskets. Basketry is produced much like woven cloth: long strips of material are intertwined to lock strands together. However, wickerwork almost never involves anything like a loom. The usual materials are stiff enough to retain a shape and resist tangling. Basketwork is typically springy and resilient, too. Loose basketwork, leaving large gaps between strips, can provide very light storage. Exceptionally tight work with fine materials can be watertight – at least temporarily. Wicker can also be a structural material. Tight bundles of grass and reeds approach light woods in stiffness and density. Many early civilizations, including the Egyptians and many South American Indians, used boats made from bundles of reeds (see Rafts, pp. 138-139, and Reed Boats, p. 143). Such bundles were the roofing of choice for northern Europe. Tatami mats, made from reeds and straw, were an important flooring material in Japan. And small buildings worldwide have been made from woven grass and weeds on wooden frames. Like all organic matter, basketry is sensitive to moisture. It suffers more from wear than many other materials; a year’s regular use can destroy a basket. Contrary to film depictions, though, well-kept thatching doesn’t burn any more readily than solid wood. No more air reaches the inner stalks of grass than might reach the inside of a log, so only the surface burns. Poorly maintained thatching – with split bindings and frayed ends – is quick to catch fire! For the purposes of Making Things Burn (p. B433), treat thatching as resistant, becoming flammable if old and frayed. === Paper and Its Cousins === Several light, flexible surfaces were used for writing (see Flat Media, p. 46), of which paper was a relative latecomer. //Barkcloth// (TL0). The inner bark of certain trees found around the Indian and Pacific Oceans can be pounded into thin layers resembling strong, rough paper. Though mostly made into clothing, this was occasionally used for maps and other drawings. //Pith “Papers”// (TL1). Several paper-like materials are manufactured from layers of thin strips of pith from plants, laid out perpendicular to each other and pressed together. They have a natural adhesion that holds them together, though glue is often necessary to join smaller sheets into longer scrolls. In Asia, pith papers are customarily termed “rice paper,” although they’re made from several different plants. Egypt’s pith paper is papyrus, made from a species of reed. //Parchment// (TL2). Very thin hides (usually sheep or goat) can be scraped smooth or processed with lime to remove hair without scratching the skin. Parchment was first used in Anatolia as early as the second century B.C. It became the dominant writing material in temperate Europe by the Middle Ages. Unlike leather, parchment isn’t tanned, so it remains white. Particularly fine parchments are called vellum but manufactured the same way. The most prized vellum came from the skin of unborn calves, which is thin, hairless, and large enough to make it worth the trouble. //Paper// (TL3). True paper consists of small fibers suspended in water, deposited on a fine-meshed screen, and left to dry. Since paper could be made from a variety of fibers, it provided a cheaper writing medium than its predecessors. Paper originated in China, where it was known by the first century B.C. The technology spread through India and the Near East into Europe by the 12th century. Asian papers used a range of fibers, including silk and mulberry bark; Western papers were made predominantly from linen. At TL4, the Chinese began to produce paper from bamboo, reducing the cost considerably. === Organic Adhesives and Matrices === As stones were best held together by mineral mortars, organic materials were best held together by organic adhesives. //Glue// (TL0). Most low-tech glues were produced by boiling hide and connective tissue to render out collagen. Glues from fish are thin and light, and suitable for delicate jobs. Glues from mammals are thicker and heavier. Animal glue was often stored in solid form and melted or mixed with water to make it liquid again. //Plant Resins// (TL0). A variety of trees found throughout eastern Asia yield fresh resins that set on exposure to warm, moist air to produce a hard, shiny finish. These can be colored with a number of mineral pigments, or combined with ground bone and horn to create a more durable surface. Multiple layers can even be carved and polished. //Tar// (TL0). Tar or pitch is a resin derived from plants or mineral deposits. Vegetable tar is produced by gathering the runoff from charcoal-making; 40-50 lbs. of wood might yield 1 lb. of tar. Mineral tar is simply dug up. Tar is a thick liquid when heated but solid and waterproof at room temperature, making it valuable as an adhesive and as caulking for barrels and ships. Flammable but slow-burning, it can also be used to make long-burning torches. //Drying Oils// (TL1). Certain vegetable oils gradually harden on contact with air – the process being polymerization, not strictly drying – and can serve as a finish for furniture and a medium for paint. Linseed oil was the best and earliest, appearing in Egypt during the second millennium B.C. Others – including castor, poppy, safflower, soybean, tung, and walnut oil – became available by TL3. //Shellac// (TL1). An alcohol-soluble resin produced by the lac insect native to southern Asia (though it was widely exported), shellac saw initial use as both an adhesive and a red-purple dye. At TL3, it came to be employed as a protective coating on paintings and woodwork, although it was still most prized for its color. The word “lacquer” derives from the same root as “shellac,” but can refer to any resin, notably the plant resins in Asian lacquerware. //Wax// (TL1). In addition to being flammable, beeswax was used as an adhesive and a light-duty waterproof sealant. Although it’s a far worse adhesive than glue or tar, wax melts at a comfortable temperature and can be pressed into convenient shapes. ====Ultra-Tech Materials==== Ultra-tech armor may be made of tough synthetic fibers, ceramics, plastics, or alloys similar to lower-TL armor. All of these technologies improve at higher TLs due to ongoing advances in material technology, but two materials are worthy of special mention. ===Smart Bioplastic (TL10)=== This is a tough, flexible, pseudo-alive smart material. Every square inch of it contains electrically-active muscles, fibers and nerve endings. A coded electrical impulse can command these muscles to move, allowing an item constructed of bioplas to change its shape! Bioplastic is very resistant to damage. If it has access to normal air and solar radiation, it can repair itself, healing any damage it has suffered at 1 HP every six hours. (Items with 20 HP or more heal faster – see High HP and Healing, p. B424.) Bioplastic items in regular use include bioplas armor (p. 174), biosuits (p. 179), and survival modules (p. 79). Bioplastic can even be used to make houses. ===Living Metal (TL12)=== Living metal devices are assembled using advanced nanotech, but the microscopic construction robots remain active within the object after it is built. Unless the object has been totally destroyed (-5 ¥ HP or worse), any damage to the object will be regenerated in a matter of hours. Living metal items with fewer than HP 20 heal at 1 HP per hour; items with more HP heal faster (see High HP and Healing, p. B424). This repair speed assumes that no parts are missing. If part of the original device is missing, but the proper material is available very close by, the construction robots can use it to replace missing parts; this halves the “regeneration” speed for that percentage of the device that must be rebuilt from scratch. Implications of this include: Any broken fragment of a living metal device can regrow the whole device under the right circumstances. It is dangerous to set a broken living metal device on a metal surface; you may return to find the device repaired, or partially repaired, and the surface pitted where the robots took material from it! A million-year-old device made of living metal will seem as new as the day it was first built. Corrosion and other damage will have been repaired as quickly as it occurred. Powerful radiation can “kill” the robots, eliminating their self-repair capacity. Worse, it might “mutate” them, causing them to rebuild the device differently! The robots can withstand single bursts of up to 1,000 rads, or up to 500 rads in an hour. Most metallic equipment can be made of living metal for double its normal cost.