1.
Ball (association football)
–
A football, soccer ball, or association football ball is the ball used in the sport of association football. The name of the ball according to whether the sport is called football, soccer. The balls spherical shape, as well as its size, weight, additional, more stringent, standards are specified by FIFA and subordinate governing bodies for the balls used in the competitions they sanction. Early footballs began as animal bladders or stomachs that would fall apart if kicked too much. Improvements became possible in the 19th century with the introduction of rubber, the modern 32-panel ball design was developed in 1962 by Eigil Nielsen, and technological research continues today to develop footballs with improved performance. In 1863, the first specifications for footballs were laid down by the Football Association, previous to this, footballs were made out of inflated leather, with later leather coverings to help footballs maintain their shapes. In 1872 the specifications were revised, and these rules have been essentially unchanged as defined by the International Football Association Board. Differences in footballs created since this rule came into effect have been to do with the used in their creation. Footballs have gone through a change over time. During medieval times balls were made from an outer shell of leather filled with cork shavings. Another method of creating a ball was using animal bladders for the inside of the making it inflatable. However, these two styles of creating footballs made it easy for the ball to puncture and were inadequate for kicking and it was not until the 19th century that footballs developed into what a football looks like today. In 1838, Charles Goodyear introduced the use of rubber and their discoveries of vulcanisation, Vulcanization is the treatment of rubber to give it certain qualities such as strength, elasticity, and resistance to solvents. Vulcanization of rubber also helps the football resist moderate heat and cold, Vulcanization helped create inflatable bladders that pressurise the outer panel arrangement of the football. Charles Goodyears innovation increased the ability of the ball and made it easier to kick. Most of the balls of this time had tanned leather with eighteen sections stitched together and these were arranged in six panels of three strips each. During the 1900s, footballs were made out of rubber and leather which was perfect for bouncing and kicking the ball, however, when heading the football it was usually painful. This problem was most probably due to absorption of the leather from rain
2.
Adidas
–
Adidas AG is a German multinational corporation, headquartered in Herzogenaurach, Germany, that designs and manufactures shoes, clothing and accessories. It is the largest sportswear manufacturer in Europe, and the second biggest in the world, Adidas revenue for 2016 was listed at €19.29 billion. Adidas was registered on 18 August 1949 by Adolf Dassler, following a feud at the Gebrüder Dassler Schuhfabrik company between him and his older brother Rudolf. Rudolf had earlier established Puma, which became the business rival of Adidas. The companys clothing and shoe designs typically feature three parallel bars, and the motif is incorporated into Adidass current official logo. The brand name is uncapitalized and is stylized with a case a. Christoph Von Wilhelm Dassler was a worker in a shoe factory, after leaving school, their son, Rudolf Rudi Dassler, joined his father at the shoe factory. When he returned from fighting in World War I, Rudolf received a management position at a porcelain factory, Adolf Adi Dassler started to produce his own sports shoes in his mothers wash kitchen in Herzogenaurach after his return from World War I. In July 1924, his brother Rudolf returned to Herzogenaurach to join his brothers business. Following Owens haul of four medals, his success cemented the good reputation of Dassler shoes among the worlds most famous sportsmen. Letters from around the world landed on the desks. Business boomed and the Dasslers were selling 200,000 pairs of every year before World War II. After Rudolf was later picked up by American soldiers and accused of being a member of the Waffen SS, American occupying forces subsequently became major buyers of the Dassler brothers shoes. Although it is a urban myth that the name is an acronym for All Day I Dream About Sports. Puma and Adidas entered into a fierce and bitter rivalry after the split. Indeed, the town of Herzogenaurach was divided on the issue, even the towns two football clubs were divided, ASV Herzogenaurach club was supported by Adidas, while 1 FC Herzogenaurach endorsed Rudolfs footwear. When handymen were called to Rudolfs home, they would deliberately wear Adidas shoes, Rudolf would tell them to go to the basement and pick out a pair of free Pumas. The two brothers were never reconciled and although both are now buried in the cemetery, they are spaced as far apart as possible
3.
1970 FIFA World Cup
–
The 1970 FIFA World Cup was the ninth FIFA World Cup, the quadrennial international football championship for mens national teams. Held from 31 May to 21 June in Mexico, it was the first World Cup tournament staged in North America, Teams representing 75 nations from all six populated continents entered the competition, and its qualification rounds began in May 1968. Fourteen teams qualified from this process to join host nation Mexico, El Salvador, Israel, and Morocco made their first appearances at the final stage, and Peru their first since 1930. The tournament was won by Brazil, which defeated another former champion, Italy. The win gave Brazil its third World Cup title, which allowed them to keep the Jules Rimet Trophy. The victorious team, led by Carlos Alberto and featuring players such as Pelé, Gérson, Jairzinho, Rivellino and they achieved a perfect record of wins in all six games in the finals, as well as winning all their qualifying fixtures. The World Cup returned to Mexico just sixteen years later in 1986, Argentina, Australia, Colombia, Japan, Mexico and Peru were all considered to host the 1970 FIFA World Cup. Mexico was chosen as the host nation in 1964 through a vote at FIFAs congress in Tokyo on 8 October, a total of 75 teams entered the 1970 FIFA World Cup, and 73 were required to qualify. Due to rejected entries and withdrawals,68 teams eventually participated in the qualifying stages, Mexico as the host nation and England as reigning World Cup champions were granted automatic qualification, with the remaining fourteen finals places divided among the continental confederations. Eight places were available to teams from UEFA, three for CONMEBOL, one for CAF, one for an AFC/OFC team, and one for CONCACAF. The draw for the stages was conducted on 1 February 1968 in Casablanca, Morocco, with matches beginning in May 1968. North Korea, quarter-finalists at the tournament, were disqualified during the process after refusing to play in Israel for political reasons. El Salvador qualified for the finals after beating Honduras in a play-off match and those who failed to qualify included Argentina, France, Hungary, Portugal and Spain. Five stadia in five different cities were selected to host the World Cup matches, alternative venues in Hidalgo state and the port city of Veracruz were also considered. Each group was based solely in one city with exception of Group 2, aside from the Estadio Luis Dosal, all the stadia had only been constructed during the 1960s, as Mexico prepared to host both the World Cup and the 1968 Summer Olympics. The altitude of the varied and the importance of acclimatisation was strongly considered by all the participating teams. As a result, in contrast to the tournament staged in England. Some teams had already experienced the conditions when competing in the football competition at 1968 Summer Olympics
4.
Mexico
–
Mexico, officially the United Mexican States, is a federal republic in the southern half of North America. It is bordered to the north by the United States, to the south and west by the Pacific Ocean, to the southeast by Guatemala, Belize, and the Caribbean Sea, and to the east by the Gulf of Mexico. Covering almost two million square kilometers, Mexico is the sixth largest country in the Americas by total area, Mexico is a federation comprising 31 states and a federal district that is also its capital and most populous city. Other metropolises include Guadalajara, Monterrey, Puebla, Toluca, Tijuana, pre-Columbian Mexico was home to many advanced Mesoamerican civilizations, such as the Olmec, Toltec, Teotihuacan, Zapotec, Maya and Aztec before first contact with Europeans. In 1521, the Spanish Empire conquered and colonized the territory from its base in Mexico-Tenochtitlan, Three centuries later, this territory became Mexico following recognition in 1821 after the colonys Mexican War of Independence. The tumultuous post-independence period was characterized by instability and many political changes. The Mexican–American War led to the cession of the extensive northern borderlands, one-third of its territory. The Pastry War, the Franco-Mexican War, a civil war, the dictatorship was overthrown in the Mexican Revolution of 1910, which culminated with the promulgation of the 1917 Constitution and the emergence of the countrys current political system. Mexico has the fifteenth largest nominal GDP and the eleventh largest by purchasing power parity, the Mexican economy is strongly linked to those of its North American Free Trade Agreement partners, especially the United States. Mexico was the first Latin American member of the Organisation for Economic Co-operation and Development and it is classified as an upper-middle income country by the World Bank and a newly industrialized country by several analysts. By 2050, Mexico could become the fifth or seventh largest economy. The country is considered both a power and middle power, and is often identified as an emerging global power. Due to its culture and history, Mexico ranks first in the Americas. Mexico is a country, ranking fourth in the world by biodiversity. In 2015 it was the 9th most visited country in the world, Mexico is a member of the United Nations, the World Trade Organization, the G8+5, the G20, the Uniting for Consensus and the Pacific Alliance. Mēxihco is the Nahuatl term for the heartland of the Aztec Empire, namely, the Valley of Mexico, and its people, the Mexica and this became the future State of Mexico as a division of New Spain prior to independence. It is generally considered to be a toponym for the valley became the primary ethnonym for the Aztec Triple Alliance as a result. After New Spain won independence from Spain, representatives decided to name the new country after its capital and this was founded in 1524 on top of the ancient Mexica capital of Mexico-Tenochtitlan
5.
1974 FIFA World Cup
–
The 1974 FIFA World Cup, the tenth staging of the World Cup, was held in West Germany from 13 June to 7 July. The tournament marked the first time that the current trophy, the FIFA World Cup Trophy, the previous trophy, the Jules Rimet Trophy, had been won for the third time by Brazil in 1970 and awarded permanently to the Brazilians. The host nation won the title beating the Netherlands in the final, the victory was the second for West Germany, who had also won in 1954. Australia, East Germany, Haiti and Zaire made their first appearances at the stage. West Germany was chosen as the host nation by FIFA in London, hosting rights for the 1978 and 1982 tournaments were awarded at the same time. West Germany agreed a deal with Spain by which Spain would support West Germany for the 1974 tournament, ninety-eight countries took part in the qualifying tournament, and some of footballs most successful nations did not qualify. The USSR was disqualified after the playoff against Chile,16 teams qualified, divided into four groups of four. Each played a round-robin with two points for a win and one for a draw, and goal difference used to separate teams level on points, the top two teams from each group advanced to the next stage. However, in a change from the used in the previous five competitions, the second round consisted of another group stage. The winners of each played each other in the final. The tournament was held mostly in bad weather, and the stadia had few protected places, few western European nations had qualified, of which most were eliminated early. Fans from the Eastern neighbor states were hindered by political circumstances, carlos Caszely of Chile became the first player to be sent off with a red card in a World Cup match, during their match against West Germany. Red cards were introduced in World Cup play in 1970. Two teams made a powerful impact on the first round. The Dutch marked their first World Cup finals since 1938 by topping their group, with wins over Uruguay and Bulgaria. Sweden joined the Dutch in the group round after beating Uruguay 3–0. Poland, meanwhile, took points from a group containing two of the favourites for the tournament. They beat Argentina 3–2, trounced Haiti 7–0, then beat Italy 2–1 – a result that knocked the Italians out of the Cup, while Haiti didnt do particularly well in their first World Cup finals they did have one moment of glory
6.
West Germany
–
West Germany is the common English name for the Federal Republic of Germany or FRG in the period between its creation on 23 May 1949 to German reunification on 3 October 1990. During this Cold War era, NATO-aligned West Germany and Warsaw Pact-aligned East Germany were divided by the Inner German border, after 1961 West Berlin was physically separated from East Berlin as well as from East Germany by the Berlin Wall. This situation ended when East Germany was dissolved and its five states joined the ten states of the Federal Republic of Germany along with the reunified city-state of Berlin. With the reunification of West and East Germany, the Federal Republic of Germany, enlarged now to sixteen states and this period is referred to as the Bonn Republic by historians, alluding to the interwar Weimar Republic and the post-reunification Berlin Republic. The Federal Republic of Germany was established from eleven states formed in the three Allied Zones of occupation held by the United States, the United Kingdom and France, US and British forces remained in the country throughout the Cold War. Its population grew from roughly 51 million in 1950 to more than 63 million in 1990, the city of Bonn was its de facto capital city. The fourth Allied occupation zone was held by the Soviet Union, as a result, West Germany had a territory about half the size of the interbellum democratic Weimar Republic. At the onset of the Cold War, Europe was divided among the Western and Eastern blocs, Germany was de facto divided into two countries and two special territories, the Saarland and divided Berlin. The Federal Republic of Germany claimed a mandate for all of Germany. It took the line that the GDR was an illegally constituted puppet state, though the GDR did hold regular elections, these were not free and fair. For all practical purposes the GDR was a Soviet puppet state, from the West German perspective the GDR was therefore illegitimate. Three southwestern states of West Germany merged to form Baden-Württemberg in 1952, in addition to the resulting ten states, West Berlin was considered an unofficial de facto 11th state. It recognised the GDR as a de facto government within a single German nation that in turn was represented de jure by the West German state alone. From 1973 onward, East Germany recognised the existence of two German countries de jure, and the West as both de facto and de jure foreign country, the Federal Republic and the GDR agreed that neither of them could speak in the name of the other. The first chancellor Konrad Adenauer, who remained in office until 1963, had worked for an alignment with NATO rather than neutrality. He not only secured a membership in NATO but was also a proponent of agreements that developed into the present-day European Union, when the G6 was established in 1975, there was no question whether the Federal Republic of Germany would be a member as well. With the collapse of communism in Central and Eastern Europe in 1989, symbolised by the opening of the Berlin Wall, East Germany voted to dissolve itself and accede to the Federal Republic in 1990. Its five post-war states were reconstituted along with the reunited Berlin and they formally joined the Federal Republic on 3 October 1990, raising the number of states from 10 to 16, ending the division of Germany
7.
UEFA Euro 1972
–
The 1972 UEFA European Football Championship final tournament was held in Belgium. This was the fourth European Football Championship, held four years. The final tournament took place between 14 and 18 June 1972, at the time, only four countries could play the final tournament which meant that there were only the semi-finals, the final and the third place match. The hosts were announced after the qualifying round, which meant all teams had to participate in the qualification process for the final stage. Belgium was chosen among three candidates, the bids came from England and Italy, whose teams did not reach the semi-finals. West Germany won the tournament, beating the Soviet Union 3–0 in the final, with coming from Gerd Müller. The qualifying round was played throughout 1970 and 1971, and 1972, there were eight qualifying groups of four teams each. The matches were played in a home-and-away basis, victories were worth 2 points, draws 1 point, and defeats 0 points. Only group winners could qualify for the quarter-finals, the quarter-finals were played in two legs on a home-and-away basis. The winners of the quarter-finals would go through to the final tournament, fastest goal,24 minutes Raoul Lambert Gerd Müller With four goals, Gerd Müller is the top scorer in the tournament. In total,10 goals were scored by 7 different players in 4 matches, none of the goals is credited as own goal. 4 goals Gerd Müller 1 goal Herbert Wimmer Anatoli Konkov Raoul Lambert Odilon Polleunis Paul Van Himst Lajos Kű UEFA Team of the Tournament EURO1972 Official History
8.
Truncated icosahedron
–
In geometry, the truncated icosahedron is an Archimedean solid, one of 13 convex isogonal nonprismatic solids whose faces are two or more types of regular polygons. It has 12 regular pentagonal faces,20 regular hexagonal faces,60 vertices and 90 edges and it is the Goldberg polyhedron GPV or 1,1, containing pentagonal and hexagonal faces. This geometry is associated with footballs typically patterned with white hexagons, geodesic domes such as those whose architecture Buckminster Fuller pioneered are often based on this structure. It also corresponds to the geometry of the fullerene C60 molecule and it is used in the cell-transitive hyperbolic space-filling tessellation, the bitruncated order-5 dodecahedral honeycomb. This polyhedron can be constructed from an icosahedron with the 12 vertices truncated such that one third of each edge is cut off at each of both ends and this creates 12 new pentagon faces, and leaves the original 20 triangle faces as regular hexagons. Thus the length of the edges is one third of that of the original edges, cartesian coordinates for the vertices of a truncated icosahedron centered at the origin are all even permutations of, where φ =1 + √5/2 is the golden mean. Using φ2 = φ +1 one verifies that all vertices are on a sphere, centered at the origin, with the radius equal to √9φ +10. Permutations, X axis Y axis Z axis The truncated icosahedron has five special orthogonal projections, centered, on a vertex, the last two correspond to the A2 and H2 Coxeter planes. The truncated icosahedron can also be represented as a spherical tiling and this projection is conformal, preserving angles but not areas or lengths. Straight lines on the sphere are projected as circular arcs on the plane and this result is easy to get by using one of the three orthogonal golden rectangles drawn into the original icosahedron as the starting point for our considerations. The angle between the segments joining the center and the vertices connected by shared edge is approximately 23. 281446°. The area A and the volume V of the truncated icosahedron of edge length a are, with unit edges, the surface area is 21 for the pentagons and 52 for the hexagons, together 73. The truncated icosahedron easily demonstrates the Euler characteristic,32 +60 −90 =2, the balls used in association football and team handball are perhaps the best-known example of a spherical polyhedron analog to the truncated icosahedron, found in everyday life. The ball comprises the same pattern of regular pentagons and regular hexagons, but it is more due to the pressure of the air inside. This ball type was introduced to the World Cup in 1970, geodesic domes are typically based on triangular facetings of this geometry with example structures found across the world, popularized by Buckminster Fuller. A variation of the icosahedron was used as the basis of the wheels used by the Pontiac Motor Division between 1971 and 1976 on its Trans Am and Grand Prix. This shape was also the configuration of the used for focusing the explosive shock waves of the detonators in both the gadget and Fat Man atomic bombs. The truncated icosahedron can also be described as a model of the Buckminsterfullerene, or buckyball, molecule, an allotrope of elemental carbon, discovered in 1985
9.
Pentagon
–
In geometry, a pentagon is any five-sided polygon or 5-gon. The sum of the angles in a simple pentagon is 540°. A pentagon may be simple or self-intersecting, a self-intersecting regular pentagon is called a pentagram. A regular pentagon has Schläfli symbol and interior angles are 108°, a regular pentagon has five lines of reflectional symmetry, and rotational symmetry of order 5. The diagonals of a regular pentagon are in the golden ratio to its sides. The area of a regular convex pentagon with side length t is given by A = t 225 +1054 =5 t 2 tan 4 ≈1.720 t 2. A pentagram or pentangle is a regular star pentagon and its sides form the diagonals of a regular convex pentagon – in this arrangement the sides of the two pentagons are in the golden ratio. The area of any polygon is, A =12 P r where P is the perimeter of the polygon. Substituting the regular pentagons values for P and r gives the formula A =12 ×5 t × t tan 2 =5 t 2 tan 4 with side length t, like every regular convex polygon, the regular convex pentagon has an inscribed circle. The apothem, which is the r of the inscribed circle. Like every regular polygon, the regular convex pentagon has a circumscribed circle. For a regular pentagon with successive vertices A, B, C, D, E, the regular pentagon is constructible with compass and straightedge, as 5 is a Fermat prime. A variety of methods are known for constructing a regular pentagon, one method to construct a regular pentagon in a given circle is described by Richmond and further discussed in Cromwells Polyhedra. The top panel shows the construction used in Richmonds method to create the side of the inscribed pentagon, the circle defining the pentagon has unit radius. Its center is located at point C and a midpoint M is marked halfway along its radius and this point is joined to the periphery vertically above the center at point D. Angle CMD is bisected, and the bisector intersects the axis at point Q. A horizontal line through Q intersects the circle at point P, to determine the length of this side, the two right triangles DCM and QCM are depicted below the circle. Using Pythagoras theorem and two sides, the hypotenuse of the triangle is found as 5 /2
10.
Hexagon
–
In geometry, a hexagon is a six sided polygon or 6-gon. The total of the angles of any hexagon is 720°. A regular hexagon has Schläfli symbol and can also be constructed as an equilateral triangle, t. A regular hexagon is defined as a hexagon that is both equilateral and equiangular and it is bicentric, meaning that it is both cyclic and tangential. The common length of the sides equals the radius of the circumscribed circle, all internal angles are 120 degrees. A regular hexagon has 6 rotational symmetries and 6 reflection symmetries, the longest diagonals of a regular hexagon, connecting diametrically opposite vertices, are twice the length of one side. Like squares and equilateral triangles, regular hexagons fit together without any gaps to tile the plane, the cells of a beehive honeycomb are hexagonal for this reason and because the shape makes efficient use of space and building materials. The Voronoi diagram of a triangular lattice is the honeycomb tessellation of hexagons. It is not usually considered a triambus, although it is equilateral, the maximal diameter, D is twice the maximal radius or circumradius, R, which equals the side length, t. The minimal diameter or the diameter of the circle, d, is twice the minimal radius or inradius. If a regular hexagon has successive vertices A, B, C, D, E, F, the regular hexagon has Dih6 symmetry, order 12. There are 3 dihedral subgroups, Dih3, Dih2, and Dih1, and 4 cyclic subgroups, Z6, Z3, Z2 and these symmetries express 9 distinct symmetries of a regular hexagon. John Conway labels these by a letter and group order, r12 is full symmetry, and a1 is no symmetry. These two forms are duals of each other and have half the order of the regular hexagon. The i4 forms are regular hexagons flattened or stretched along one symmetry direction and it can be seen as an elongated rhombus, while d2 and p2 can be seen as horizontally and vertically elongated kites. G2 hexagons, with sides parallel are also called hexagonal parallelogons. Each subgroup symmetry allows one or more degrees of freedom for irregular forms, only the g6 subgroup has no degrees of freedom but can seen as directed edges. Hexagons of symmetry g2, i4, and r12, as parallelogons can tessellate the Euclidean plane by translation, other hexagon shapes can tile the plane with different orientations
11.
AT&T
–
AT&T Inc. is an American multinational telecommunications conglomerate, headquartered at Whitacre Tower in downtown Dallas, Texas. AT&T is the third-largest company in Texas, as of February 2017, AT&T is the 12th largest company in the world as measured by a composite of revenues, profits, assets and market valuation. AT&T is the largest telecommunications company in the world by revenue, as of 2017, it is also the 18th-largest mobile telecom operator in the world, with 135 million mobile customers. AT&T was ranked at #4 on the 2017 rankings of the worlds most valuable brands published by Brand Finance, Southwestern Bell changed its name to SBC Communications Inc. in 1995. In 2005, SBC purchased former parent AT&T Corp. and took on its branding, with the merged entity naming itself AT&T Inc. and using the iconic AT&T Corp. logo and stock-trading symbol. The current AT&T reconstitutes much of the former Bell System and includes ten of the original 22 Bell Operating Companies, AT&T can trace its origin back to the original Bell Telephone Company founded by Alexander Graham Bell after his invention of the telephone. This monopoly was known as the Bell System, and during this period, for periods of time, the former AT&T was the worlds largest phone company. In 1982, U. S. regulators broke up the AT&T monopoly, requiring AT&T to divest its regional subsidiaries and these new companies were known as Regional Bell Operating Companies, or more informally, Baby Bells. AT&T continued to long distance services, but as a result of this breakup, faced competition from new competitors such as MCI. Southwestern Bell was one of the created by the breakup of AT&T. The architect of divestiture for Southwestern Bell was Robert G. Pope, the company soon started a series of acquisitions. This includes the 1987 acquisition of Metromedia mobile business, and the acquisition of several companies in the early 1990s. In the later half of the 1990s, the company acquired several other companies, including some Baby Bells. During this time, the changed its name to SBC Communications. By 1998, the company was in the top 15 of the Fortune 500, in 2005, SBC purchased AT&T for $16 billion. After this purchase, SBC adopted the better-known AT&T name and brand, the current AT&T claims the original AT&Ts history as its own, though its corporate structure only dates from 1983. It also retains SBCs pre-2005 stock price history, in September 2013, AT&T announced it would expand into Latin America through a collaboration with Carlos Slims América Móvil. In December 2013, AT&T announced plans to sell its Connecticut wireline operations to Stamford-based Frontier Communications, in July 2015, AT&T purchased DirecTV for $48.5 billion, or $67.1 billion including assumed debt
12.
Leather
–
Leather is a durable and flexible material created by tanning animal rawhide and skin, often cattle hide. It can be produced at manufacturing scales ranging from cottage industry to heavy industry, people use leather to make various goods—including clothing, bookbinding, leather wallpaper, and as a furniture covering. It is produced in a variety of types and styles. Several tanning processes transform hides and skins into leather, Chrome-tanned leather, invented in 1858, is tanned using chromium sulfate and it is more supple and pliable than vegetable-tanned leather and does not discolor or lose shape as drastically in water as vegetable-tanned. It is also known as wet-blue for its color derived from the chromium, more exotic colors are possible when using chrome tanning. The chrome tanning method usually only takes a day to finish, and it is reported that chrome-tanned leather adds up to 80% of the global leather supply. Vegetable-tanned leather is tanned using tannins and other found in different vegetable matter, such as tree bark prepared in bark mills, wood, leaves, fruits. It is supple and brown in color, with the exact shade depending on the mix of chemicals and it is the only form of leather suitable for use in leather carving or stamping. Vegetable-tanned leather is not stable in water, it tends to discolor, so if left to soak and then dried it shrinks, in hot water, it shrinks drastically and partly congeals—becoming rigid, and eventually brittle. Boiled leather is an example of this, where the leather has been hardened by being immersed in hot water, historically, it was occasionally used as armour after hardening, and it has also been used for book binding. Aldehyde-tanned leather is tanned using glutaraldehyde or oxazolidine compounds and this is the leather that most tanners refer to as wet-white leather due to its pale cream or white color. It is the type of chrome-free leather, often seen in shoes for infants. Formaldehyde tanning is another aldehyde tanning method, brain-tanned leathers fall into this category, and are exceptionally water absorbent. Brain tanned leathers are made by a process that uses emulsified oils, often those of animal brains such as deer, cattle. They are known for their softness and washability. Chamois leather also falls into the category of aldehyde tanning, and like brain tanning, produces a porous, chamois leather is made using marine oils that oxidize easily to produce the aldehydes that tan the leather to color it. Rose-tanned leather is a variation of oil tanning and brain tanning. Rose-tanned leather tanned leaves a powerful rose fragrance even years from when it is manufactured and it has been called the most valuable leather on earth, but this is mostly due to the high cost of rose otto and its labor-intensive tanning process
