A passport is a travel document issued by a country's government, that certifies the identity and nationality of its holder for the purpose of international travel. Standard passports may contain information such as the holder's name and date of birth, photograph and other identifying information. Many countries are moving towards including biometric information in a microchip embedded in the passport, making them machine-readable and difficult to counterfeit; as of January 2019, there are over 150 jurisdictions issuing these e-Passports. Issued passports remain valid until each expires. A passport holder is entitled to enter the country that issued the passport, though some people entitled to a passport may not be full citizens with right of abode. A passport does not of itself create any rights in the country being visited or obligate the issue country in any way, such as providing consular assistance; some passports attest to status as a diplomat or other official, entitled to rights and privileges such as immunity from arrest or prosecution.
Many countries allow entry to holders of passports of other countries, sometimes requiring a visa to be obtained, but this is not an automatic right. Many other additional conditions, such as not being to become a public charge for financial or other reasons, the holder not having been convicted of a crime, may apply. Where a country does not recognise another, or is in dispute with it, it may prohibit the use of their passport for travel to that other country, or may prohibit entry to holders of that other country's passports, sometimes to others who have, for example, visited the other country; some countries and international organisations issue travel documents which are not standard passports, but enable the holder to travel internationally to countries that recognise the documents. For example, stateless persons are not issued a national passport, but may be able to obtain a refugee travel document or the earlier "Nansen passport" which enables them to travel to countries which recognise the document, sometimes to return to the issuing country.
Passports are requested in other circumstances to confirm identification such as checking in to a hotel or when changing money to a local currency. One of the earliest known references to paperwork that served in a role similar to that of a passport is found in the Hebrew Bible. Nehemiah 2:7–9, dating from 450 BC, states that Nehemiah, an official serving King Artaxerxes I of Persia, asked permission to travel to Judea. Passports were an important part of the Chinese bureaucracy as early as the Western Han, if not in the Qin Dynasty, they required such details as age and bodily features. These passports determined a person's ability to move throughout imperial counties and through points of control. Children needed passports, but those of one year or less who were in their mother's care might not have needed them. In the medieval Islamic Caliphate, a form of passport was a receipt for taxes paid. Only people who paid their zakah or jizya taxes were permitted to travel to different regions of the Caliphate.
In medieval Europe, such documents were issued to foreign travelers by local authorities and contained a list of towns and cities the document holder was permitted to enter or pass through. On the whole, documents were not required for travel to sea ports, which were considered open trading points, but documents were required to travel inland from sea ports. King Henry V of England is credited with having invented what some consider the first passport in the modern sense, as a means of helping his subjects prove who they were in foreign lands; the earliest reference to these documents is found in a 1414 Act of Parliament. In 1540, granting travel documents in England became a role of the Privy Council of England, it was around this time that the term "passport" was used. In 1794, issuing British passports became the job of the Office of the Secretary of State; the 1548 Imperial Diet of Augsburg required the public to hold imperial documents for travel, at the risk of permanent exile. A rapid expansion of railway infrastructure and wealth in Europe beginning in the mid-nineteenth century led to large increases in the volume of international travel and a consequent unique dilution of the passport system for thirty years prior to World War I.
The speed of trains, as well as the number of passengers that crossed multiple borders, made enforcement of passport laws difficult. The general reaction was the relaxation of passport requirements. In the part of the nineteenth century and up to World War I, passports were not required, on the whole, for travel within Europe, crossing a border was a straightforward procedure. Comparatively few people held passports. During World War I, European governments introduced border passport requirements for security reasons, to control the emigration of people with useful skills; these controls remained in place after the war, becoming a standard, though controversial, procedure. British tourists of the 1920s complained about attached photographs and physical descriptions, which they considered led to a "nasty dehumanization". In 1920, the League of Nations held
A lunch box, spelled lunchbox in all UK and US dictionaries referred to as a lunch pail or lunch kit, is used to store food to be taken anywhere. The concept of a food container has existed for a long time, but it was not until people began using tobacco tins to carry meals in the early 20th century, followed by the use of lithographed images on metal, that the containers became a staple of youth, a marketable product; the lunch box has most been used by schoolchildren to take packed lunches, or a snack, from home to school. The most common modern form is a small case with a clasp and handle printed with a colorful image that can either be generic or based on children's television shows or films. Use of lithographed metal to produce lunch boxes in the 1950s, 1960s, 1970s and 1980s gave way in the 1990s to use of injection-molded plastic. A lunch kit comprises a matching vacuum bottle. However, pop culture has more embraced the singular term lunch box, now most used. With increasing industrialization resulting in Americans working outside the home in factories, it became unfeasible to go home to lunch every day, thus it was necessary to have something to protect and transport a meal.
Since the 19th century, American industrial workers have used sturdy containers to hold hardy lunches, consisting of foods such as hard-boiled eggs, meat and pie. David Shayt, curator of the Smithsonian National Museum of American History, states that “Some of our earliest examples, from the 19th century, were woven baskets with handles. A meal would be wrapped in a handkerchief. Depending on your station, a fancy wooden box would be used by the wealthy.” Tinplate boxes and recycled biscuit tins were used in the early 1800s, fitted metal pails and boxes began to appear around the 1850s. Patents started to appear for lunchbox inventions in the 1860s; the Thermos, a vacuum flask adapted for lunch box use, was introduced in 1904. The Thermos, which enabled hot or cold beverages to remain at optimal temperature until lunchtime, became a common component of the lunch box. Lunch boxes have been manufactured using various materials. Children's school lunch boxes are made of plastic or vinyl, while adult workers' lunch boxes are made of metal, such as tin or aluminium, due to the greater need for durability.
The aluminium variant was invented in 1954 by Leo May, a miner in Sudbury, after he accidentally crushed his tin lunch box. In 1935, Geuder and Frey produced the first licensed character lunch box, Mickey Mouse, it was a lithographed oval tin, with a pull-out tray inside. It did have a handle. In 1950, Aladdin Industries created the first children's lunch box based on a television show, Hopalong Cassidy; the Hopalong Cassidy lunch kit, or "Hoppy," became Aladdin’s cash cow. Debuting in time for back-to-school 1950, it would go on to sell 600,000 units in its first year alone, each at a modest $2.39 USD. While television was experiencing amazing growth during the 1950s, manufacturers saw a potential for sales. Manufacturers grew to include ADCO Liberty, American Thermos, Kruger Manufacturing Company, Landers and Clark, Okay Industries, a number of other producers through the 1980s; the first use of plastics was the lunch box handle, but spread to the entire box, with the first molded plastic boxes produced during the 1960s.
Vinyl lunch boxes debuted in 1959. During the 1960s, the lunch box had few changes; the vacuum bottle included in them, however evolved during the course of the decade and into the 1970s. What was a steel vacuum bottle with glass liner, cork or rubber stopper, bakelite cup became an all-plastic bottle, with insulated foam rather than vacuum. Aladdin produced glass liners into the 1970s. In some South American countries, a lunch box is called "lonchera" among school children, in clear assimilation of the English word "lunch". Today, lunch boxes are made of plastic, with foam insulation, an aluminum/vinyl interior; as a result, they are much better at retaining their temperature but are less rigid/protective. Other popular options include lunch boxes made of glass and metal lunch boxes, each offering different advantages. For instance, glass lunch boxes are heavier and prone to break, but are nonetheless microwavable, thereby allowing the option to heat food using a microwave. In contrast, metal lunch boxes, which are made of stainless steel, are lighter and more durable, but cannot be heated in a microwave..
Some lunch boxes, including those from the 1950s and 1960s, sometimes sell into the dozens of dollars. A Superman DVD set was released in a case resembling a tin lunch box, albeit notably smaller. A Nintendo DS starter kit was released in a case resembling a tin lunch box with New Super Mario Bros. graphics. The collector's edition of Fallout 3 was made available in a metal Vault-Tec lunch box, the likes of which can be found throughout the game world itself. Health concerns came to light in August 2002, when the Center for Environmental Health discovered that many popular vinyl lunch boxes contained dangerously high levels of lead. Many, though not all, were pulled from the shelves. In 2001, most major manufacturers began testing their lunch boxes for lead levels, remedied the issue, labeled their boxes as lead free. In the United States, the lunch box or lunch pail has been used as a symbol of the working class; the phrase'lunch pail Democrat' is used to classify populist politicians who attempt to gain the votes of the working class.
Bento – Japan Dosirak – Korea Tiffin carrier – India Tiffin box – Bangladesh Media related to
A coin is a small, round piece of metal or plastic used as a medium of exchange or legal tender. They are standardized in weight, produced in large quantities at a mint in order to facilitate trade, they are most issued by a government. Coins are metal or alloy, or sometimes made of synthetic materials, they are disc shaped. Coins made of valuable metal are stored in large quantities as bullion coins. Other coins are used as money in everyday transactions; the highest value coin in circulation is worth less than the lowest-value note. In the last hundred years, the face value of circulation coins has been lower than the value of the metal they contain, for example due to inflation. If the difference becomes significant, the issuing authority may decide to withdraw these coins from circulation issuing new equivalents with a different composition, or the public may decide to melt the coins down or hoard them. Exceptions to the rule of face value being higher than content value occur for some bullion coins made of copper, silver, or gold, intended for collectors or investors in precious metals.
Examples of modern gold collector/investor coins include the British sovereign minted by the United Kingdom, the American Gold Eagle minted by the United States, the Canadian Gold Maple Leaf minted by Canada, the Krugerrand, minted by South Africa. While the Eagle, Maple Leaf, Sovereign coins have nominal face values, the Krugerrand does not. A great quantity of coinage metals and other materials have been used to produce coins for circulation and metal investment: bullion coins serve as more convenient stores of assured metal quantity and purity than other bullion. Metal ingots, silver bullion or unmarked bars were in use for exchange among many of the civilizations that mastered metallurgy; the weight and purity of bullion would be the key determinant of value. In the Achaemenid Empire in the early 6th century BC, coinage was yet unknown, barter and to some extent silver bullion was used instead for trade; the practice of using silver bars for currency seems to have been current in Central Asia from the 6th century BC.
Coins were an evolution of "currency" systems of the Late Bronze Age, where standard-sized ingots, tokens such as knife money, were used to store and transfer value. In the late Chinese Bronze Age, standardized cast tokens were made, such as those discovered in a tomb near Anyang; these were replicas in bronze of earlier Chinese currency, cowrie shells, so they were named Bronze Shell. The earliest coins are associated with Iron Age Anatolia of the late 7th century BC, with the kingdom of Lydia. Early electrum coins were not standardized in weight, in their earliest stage may have been ritual objects, such as badges or medals, issued by priests; the unpredictability of the composition of occurring electrum implied that it had a variable value, which hampered its development. Most of the early Lydian coins include no writing, only an image of a symbolic animal. Therefore, the dating of these coins relies on archaeological evidence, with the most cited evidence coming from excavations at the Temple of Artemis at Ephesus called the Ephesian Artemision, site of the earliest known deposit of electrum coins.
Because the oldest lion head "coins" were discovered in that temple, they do not appear to have been used in commerce, these objects may not have been coins but badges or medals issued by the priests of that temple. Anatolian Artemis was the Πὀτνια Θηρῶν, it took some time before ancient coins were used for trade. The smallest-denomination electrum coins worth about a day's subsistence, would have been too valuable for buying a loaf of bread; the first coins to be used for retailing on a large-scale basis were small silver fractions, Ancient Greek coinage minted by the Ionian Greeks in the late sixth century BC. Many early Lydian and Greek coins were minted under the authority of private individuals and are thus more akin to tokens or badges than to modern coins, though due to their numbers it is evident that some were official state issues; the earliest inscribed coins are those of Phanes, dated to 625–600 BC from Ephesus in Ionia, with the legend ΦΑΝΕΟΣ ΕΜΙ ΣΗΜΑ, or just bearing the name ΦΑΝΕΟΣ.
The first electrum coins issued by a monarch are those minted by king Alyattes of Lydia, for which reason this king is sometimes mentioned as the originator of coinage. The successor of Alyattes, king Croesus, became associated with great wealth in Greek historiography, he is credited with issuing the Croeseid, the first true gold coins with a standardised purity for general circulation. And the world's first bimetallic monetary system circa 550 BCE. Herodotus mentioned the innovation made by the Lydians: "So far as we have any knowledge, they were the first people to introduce the use of gold and silver coins, the first who sold goods by retail" Coins spread in the 6th and 5th centuries BC, leading to the development of Ancient Greek coinage and Achaemenid coinage, further to Illyrian coinage. Standardized Roman currency
Punk fashion is the clothing, cosmetics and body modifications of the punk subculture. Punk fashion varies ranging from Vivienne Westwood designs to styles modeled on bands like The Exploited to the dressed-down look of North American hardcore; the distinct social dress of other subcultures and art movements, including glam rock, rude boys and mods have influenced punk fashion. Punk fashion has influenced the styles of these groups, as well as those of popular culture. Many punks use clothing as a way of making a statement. Punk fashion has been commercialized at various times, many well-established fashion designers – such as Anna Sui, Vivienne Westwood and Jean Paul Gaultier – have used punk elements in their production. Original UK Punk clothing, handmade, became mass-produced and sold in record stores and some smaller specialty clothing stores by the 1980s. Many fashion magazines and other glamour-oriented media have featured classic punk hairstyles and punk-influenced clothing. Punk rock was an intentional rebuttal of the perceived excess and pretension found in mainstream music, early punk artists' fashion was defiantly anti-materialistic.
Unkempt short hairstyles replaced the long-hair hippie look and the elaborate 1970s rock and disco styles. In the United States, simple clothes – ranging from the T-shirt/jeans/leather jacket Ramones look to the low-class, second-hand "dress" clothes of acts like Television or Patti Smith – were preferred over the expensive or colorful clothing popular in the disco scene. With her designs for The Rocky Horror Show and The Rocky Horror Picture Show, Sue Blane is credited with creating the look that became the template for punk rock fashion. In the United Kingdom, 1970s punk fashion influenced the designs of Vivienne Westwood and Malcolm McLaren and the Bromley Contingent. Mainstream punk style was influenced by clothes sold in Malcolm McLaren's shop, artdesigncafe. McLaren has credited this style to his first impressions of Richard Hell, while McLaren was in New York City working with New York Dolls. Deliberately offensive T-shirts were popular in the early punk scene, such as the DESTROY T-shirt sold at SEX, which featured an inverted crucifix and a Nazi Swastika.
Another offensive T-shirt, still seen in punk is called Snow White and the Sir Punks, features Snow White being held down and raped by five of the seven dwarfs, whilst the other two engage in anal sex. The image's origin is as part of The Realist magazine's Disneyland Memorial Orgy poster in May 1967, although the T-shirts made the scene more explicit; these T-shirts, like other punk clothing items, were torn on purpose. Other items in early British punk fashion included: leather jackets. Other accoutrements worn by some punks included: BDSM fashions. Many female punks rebelled against the stereotypical image of a woman by combining clothes that were delicate or pretty with clothes that were considered masculine, such as combining a Ballet tutu with big, clunky boots. Musician PJ Harvey was noted as "appear immersed in rock'n' roll" around the time of her album Dry in 1992, due in part to her "leather apparel, hair in a bun and black bovver boots". Punk clothing sometimes incorporated everyday objects for aesthetic effect.
Purposely ripped clothes were wrapped with tape. Other items added as jewellery included razor blades and chains. Leather and vinyl clothing have been common due to their connection with transgressive sexual practices, such as bondage and S&M. Preferred footwear included military boots, motorcycle boots, brothel creepers, Puma Clydes, Chuck Taylor All-Stars and Dr. Martens boots. Tapered jeans, tight leather pants, trousers with leopard patterns and bondage pants were popular choices. Other early punks imitated the Droogs from A Clockwork Orange by wearing bowler braces. Hair was cropped and deliberately made to look messy, was dyed bright unnatural colours. Although provocative, these hairstyles were not as extreme as punk hairstyle. In the 1980s, new fashion styles developed as parallel resurgences occurred in the United States and United Kingdom. What many recognize as typical punk fashions today emerged from the 1980s British scene, when punk underwent its Oi!/street punk, UK82 renaissance.
The US scene was exemplified by hardcore bands such as Black Flag, Minor Threat, Fear. The 1980s American scene spawned a utilitarian anti-fashion, nonetheless raw and intimidating. However, elements of the 1970s punk look never died away; some of the following clothing items were common on both sides of the Atlantic Ocean, some were unique to certain geographic areas. Footwear, common in the 1980s punk scene included Dr. Martens boots, motorcycle boots and combat boots. Jeans and tartan kilts or skirts were worn. Leather skirts became a popular item for female punks. Heavy chains were sometimes used as belts. Bullet belts, studded belts became common; some punks bought T-shirts or plaid flannel shirts and wrote political slogans
A textile is a flexible material consisting of a network of natural or artificial fibers. Yarn is produced by spinning raw fibres of wool, cotton, hemp, or other materials to produce long strands. Textiles are formed by weaving, crocheting, knotting or tatting, felting, or braiding; the related words "fabric" and "cloth" and "material" are used in textile assembly trades as synonyms for textile. However, there are subtle differences in these terms in specialized usage. A textile is any material made of interlacing fibres, including carpeting and geotextiles. A fabric is a material made through weaving, spreading, crocheting, or bonding that may be used in production of further goods. Cloth may be used synonymously with fabric but is a piece of fabric, processed; the word'textile' is from Latin, from the adjective textilis, meaning'woven', from textus, the past participle of the verb texere,'to weave'. The word'fabric' derives from Latin, most from the Middle French fabrique, or'building, thing made', earlier as the Latin fabrica'workshop.
The word'cloth' derives from the Old English clað, meaning a cloth, woven or felted material to wrap around one, from Proto-Germanic kalithaz. The first clothes, worn at least 70,000 years ago and much earlier, were made of animal skins and helped protect early humans from the ice ages. At some point people learned to weave plant fibers into textiles; the discovery of dyed flax fibres in a cave in the Republic of Georgia dated to 34,000 BCE suggests textile-like materials were made in prehistoric times. The production of textiles is a craft whose speed and scale of production has been altered beyond recognition by industrialization and the introduction of modern manufacturing techniques. However, for the main types of textiles, plain weave, twill, or satin weave, there is little difference between the ancient and modern methods. Textiles have an assortment of uses, the most common of which are for clothing and for containers such as bags and baskets. In the household they are used in carpeting, upholstered furnishings, window shades, coverings for tables and other flat surfaces, in art.
In the workplace they are used in scientific processes such as filtering. Miscellaneous uses include flags, tents, handkerchiefs, cleaning rags, transportation devices such as balloons, kites and parachutes. Textiles are used in many traditional crafts such as sewing and embroidery. Textiles for industrial purposes, chosen for characteristics other than their appearance, are referred to as technical textiles. Technical textiles include textile structures for automotive applications, medical textiles, agrotextiles, protective clothing. In all these applications stringent performance requirements must be met. Woven of threads coated with zinc oxide nanowires, laboratory fabric has been shown capable of "self-powering nanosystems" using vibrations created by everyday actions like wind or body movements. Textiles are made from many materials, with four main sources: animal, plant and synthetic; the first three are natural. In the 20th century, they were supplemented by artificial fibres made from petroleum.
Textiles are made in various strengths and degrees of durability, from the finest microfibre made of strands thinner than one denier to the sturdiest canvas. Textile manufacturing terminology has a wealth of descriptive terms, from light gauze-like gossamer to heavy grosgrain cloth and beyond. Animal textiles are made from hair, skin or silk. Wool refers to the hair of the domestic sheep or goat, distinguished from other types of animal hair in that the individual strands are coated with scales and crimped, the wool as a whole is coated with a wax mixture known as lanolin, waterproof and dirtproof. Woollen refers to a bulkier yarn produced from carded, non-parallel fibre, while worsted refers to a finer yarn spun from longer fibres which have been combed to be parallel. Wool is used for warm clothing. Cashmere, the hair of the Indian cashmere goat, mohair, the hair of the North African angora goat, are types of wool known for their softness. Other animal textiles which are made from hair or fur are alpaca wool, vicuña wool, llama wool, camel hair used in the production of coats, ponchos and other warm coverings.
Angora refers to the long, soft hair of the angora rabbit. Qiviut is the fine inner wool of the muskox. Wadmal is a coarse cloth made of wool, produced in Scandinavia 1000~1500 CE. Sea silk is an fine and valuable fabric, made from the silky filaments or byssus secreted by a gland in the foot of pen shells. Silk is an animal textile made from the fibres of the cocoon of the Chinese silkworm, spun into a smooth fabric prized for its softness. There are two main ty
Fishing tackle is the equipment used by anglers when fishing. Any equipment or gear used for fishing can be called fishing tackle; some examples are hooks, sinkers, rods, baits, spears, gaffs, traps and tackle boxes. Gear, attached to the end of a fishing line is called terminal tackle; this includes hooks, swivels, floats, split rings and wire, beads, blades and clevises to attach spinner blades to fishing lures. Sometimes the term fishing rig is used for a completed assembly of tackle ready for fishing. Fishing tackle can be contrasted with fishing techniques. Fishing tackle refers to the physical equipment, used when fishing, whereas fishing techniques refers to the manner in which the tackle is used when fishing; the term tackle, with the meaning "apparatus for fishing", has been in use from 1398 AD. Fishing tackle is called fishing gear; however the term fishing gear is more used in the context of commercial fishing, whereas fishing tackle is more used in the context of recreational fishing.
This article covers equipment used by recreational anglers. Hook and sinker is a classic combination of tackle empowering an angler to catch fish; the use of the hook in angling is descended from what would today be called a "gorge". The word "gorge", in this context, comes from an archaic word meaning "throat". Gorges were used by ancient peoples to capture fish. A gorge was a thin piece of bone or stone attached by its midpoint to a thin line; the gorge would be fixed with a bait. When a fish swallowed the bait, a tug on the line caused the gorge to orient itself at right angles to the line, thereby sticking in the fish's gullet. A fish hook is a device for catching fish either by impaling them in the mouth or, more by snagging the body of the fish. Fish hooks have been employed for millennia by anglers to catch fresh and saltwater fish. Early hooks were made from the upper bills of eagles and from bones, shells and thorns of plants. In 2005, the fish hook was chosen by Forbes as one of the top twenty tools in the history of man.
Fish hooks are attached to some form of line or lure device which connects the caught fish to the angler. There is an enormous variety of fish hooks. Sizes, designs and materials are all variable depending on the intended purpose of the hook, they are manufactured for a range of purposes from general fishing to limited and specialized applications. Fish hooks are designed to hold various types of artificial, dead or live baits. A fishing line is a cord made for fishing; the earliest fishing lines were made from leaves or plant stalk. Lines were constructed from horse hair or silk thread, with catgut leaders. From the 1850s, modern industrial machinery was employed to fashion fishing lines in quantity. Most of these lines were made from linen or silk, more cotton. Modern lines are made from artificial substances, including nylon, polyethylene and dyneema; the most common type is monofilament made of a single strand. Anglers use monofilament because of its buoyant characteristics and its ability to stretch under load.
Alternatives such as fluorocarbon, the least visible type, braided fishing line known as'superlines' because of their small diameter, minimal amount of stretch, great strength relative to standard nylon monofilament lines. Important parameters of a fishing line are its diameter. Factors that may determine what line an angler chooses for a given fishing environment include breaking strength, diameter,castability, stretch, knot strength, UV resistance, abrasion resistance, visibility. Fishing with a hook and line is called angling. In addition to the use of the hook and line used to catch a fish, a heavy fish may be landed by using a landing net or a hooked pole called a gaff. Trolling is a technique. Snagging is a technique. A sinker or plummet is a weight used when angling to force the lure or bait to sink more or to increase the distance that it may be cast; the ordinary plain sinker is traditionally made of lead. It can be any shape, is shaped round like a pipe-stem, with a swelling in the middle.
However, the use of smaller lead based fishing sinkers has now been banned in the UK, Canada and some states in the USA, since lead can cause toxic lead poisoning if ingested. There are loops of brass wire on either end of the sinker to attach the line. Weights can range from a quarter of an ounce for trout fishing up to a couple of pounds or more for sea bass and menhaden; the swivel sinker is similar to the plain one, except that instead of loops, there are swivels on each end to attach the line. This is a decided improvement, as it prevents the line from tangling. In trolling, swivel sinkers are indispensable; the slide sinker, for bottom fishing, is a leaden tube which allows the line to slip through it, when the fish bites. This is an excellent arrangement, as the angler can feel the smallest bite, whereas in the other case the fish must first move the sinker before the angler feels him. A fishing rod is an additional tool used with the hook and sinker. A length of fishing line is attached to a long, flexible rod or pole: one end terminates wit
Leather is a natural durable and flexible material created by tanning animal rawhides and skins. The most common raw material is cattle hide, it can be produced at manufacturing scales ranging from artisan to modern industrial scale. Leather is used to make a variety of articles, including footwear, automobile seats, bags, book bindings, fashion accessories, furniture, it is decorated by a wide range of techniques. The earliest record of leather artifacts dates back to 2200 BC; the leather manufacturing process is divided into three fundamental subprocesses: preparatory stages and crusting. A further subprocess, can be added into the leather process sequence, but not all leathers receive finishing; the preparatory stages are. Preparatory stages may include: soaking, liming, bating and pickling. Tanning is a process that stabilizes the proteins collagen, of the raw hide to increase the thermal and microbiological stability of the hides and skins, making it suitable for a wide variety of end applications.
The principal difference between raw and tanned hides is that raw hides dry out to form a hard, inflexible material that, when rewetted, will putrefy, while tanned material dries to a flexible form that does not become putrid when rewetted. Many tanning methods and materials exist; the typical process sees tanners load the hides into a drum and immerse them in a tank that contains the tanning "liquor". The hides soak while the drum rotates about its axis, the tanning liquor penetrates through the full thickness of the hide. Once the process achieves penetration, workers raise the liquor's pH in a process called basification, which fixes the tanning material to the leather; the more tanning material fixed, the higher the leather's hydrothermal stability and shrinkage temperature resistance. Crusting is a process that lubricates leather, it includes a coloring operation. Chemicals added during crusting must be fixed in place. Crusting culminates with a drying and softening operation, may include splitting, dyeing, whitening or other methods.
For some leathers, tanners apply a surface coating, called "finishing". Finishing operations can include oiling, buffing, polishing, glazing, or tumbling, among others. Leather can be oiled to improve its water resistance; this currying process after tanning supplements the natural oils remaining in the leather itself, which can be washed out through repeated exposure to water. Frequent oiling of leather, with mink oil, neatsfoot oil, or a similar material keeps it supple and improves its lifespan dramatically. Tanning processes differ in which chemicals are used in the tanning liquor; some common types include: Vegetable-tanned leather is tanned using tannins extracted from vegetable matter, such as tree bark prepared in bark mills. It is the oldest known method, it is supple and brown in color, with the exact shade depending on the mix of materials and the color of the skin. The color tan derives its name from the appearance of undyed vegetable-tanned leather. Vegetable-tanned leather is not stable in water.
This is a feature of oak-bark-tanned leather, exploited in traditional shoemaking. In hot water, it shrinks drastically and congeals, becoming rigid and brittle. Boiled leather is an example of this, where the leather has been hardened by being immersed in hot water, or in boiled wax or similar substances, it was used as armor after hardening, it has been used for book binding. Chrome-tanned leather, invented in 1858, is tanned using chromium other chromium salts, it is known as "wet blue" for the pale blue color of the undyed leather. The chrome tanning method takes one day to complete, making it best suited for large-scale industrial use; this is the most common method in modern use. It is more supple and pliable than vegetable-tanned leather and does not discolor or lose shape as drastically in water as vegetable-tanned. However, there are environmental concerns with this tanning method. Aldehyde-tanned leather is tanned using oxazolidine compounds, it is referred to as "wet white" due to its pale cream color.
It is the main type of "chrome-free" leather seen in shoes for infants and automobiles. Formaldehyde has been used for tanning in the past. Chamois leather is a form of aldehyde tanning that produces a porous and water-absorbent leather. Chamois leather is made using marine oils that oxidize to produce the aldehydes that tan the leather. Brain tanned leathers are made by a labor-intensive process that uses emulsified oils those of animal brains such as deer and buffalo, they are known for their exceptional washability. Alum leather is transformed using aluminium salts mixed with a variety of binders and protein sources, such as flour and egg yolk. Alum leather is not tanned. In general, leather is produced in the following grades: Top-grain leather includes the outer layer of the hide, known as the grain, which features finer, more densely packed fibers, resulting in strength and durability. Depending on thickness, it may contain some of the more fibrous under layer, known as the corium. Types of top-grain leather incl