Good Girl Gone Bad is the third studio album by Barbadian singer Rihanna. It was released on May 31, 2007, by Def Jam Recordings and SRP Records. Rihanna worked with various producers on the album, including Christopher "Tricky" Stewart, Terius "Dream" Nash, Neo da Matrix, Timbaland, Carl Sturken, Evan Rogers and StarGate. Inspired by Brandy Norwood's fourth studio album Afrodisiac (2004), Good Girl Gone Bad is a pop, dance-pop and R&B album with 1980s music influences. Described as a turning point in Rihanna's career, it represents a departure from the Caribbean sound of her previous releases, Music of the Sun (2005) and A Girl like Me (2006). Apart from the sound, she also endorsed a new image for the re lease going from an innocent girl to an edgier and more sexual look.

Critics gave generally positive reviews of the album, praising its composition and Rihanna's new musical direction, though some criticized the record's lyrics and inconsistency. The album received seven Grammy Award nominations and one win in the Best Rap/Sung Collaboration category for "Umbrella" at the 2008 ceremony. The album debuted at number two on the US Billboard 200 chart and sold 162,000 copies in its first week. Certified quintuple platinum by the Recording Industry Association of America (RIAA), it sold more than 2.8 million copies in the United States. The album reached number one in Canada, Switzerland and the United Kingdom. As of 2009, the album had sold over 7 million copies worldwide.

Good Girl Gone Bad spawned five singles, including the international hits "Umbrella" and "Don't Stop the Music"; Rolling Stone placed the former at number 412 on the magazine's 500 Greatest Songs of All Time list. In support of the album, Rihanna embarked on her first worldwide concert tour, the Good Girl Gone Bad Tour. The album was reissued as Good Girl Gone Bad: Reloaded in June 2008 with three new songs, including the Billboard Hot 100 number-one hits "Take a Bow" and "Disturbia". It was followed by Rihanna's first remix album, Good Girl Gone Bad: The Remixes, in January 2009, which featured remixes from Moto Blanco, Tony Moran, the Soul Seekerz and the Wideboys.

Background and title

Rihanna's second studio album, A Girl like Me, was released in April 2006. It is a pop-oriented record with dancehall and R&B influences. It had a mixed critical reception: some critics praised Rihanna's new musical direction, while others criticized some of the album's songs. Around its time of release, many critics felt that Rihanna's style, sound, and musical material were too similar to those of American singer Beyoncé. The album sold over 587,308 copies in the United Kingdom and more than 1,330,000 copies in the United States.

In early 2007, Rihanna began work on her third studio album. In an interview with MTV News, she announced that "the new music is going in a different direction. Not on purpose, but I just want to hear something fresh and mostly uptempo. I think that's where I want to go on this one. You feel different every album, and [at] this stage I feel like I want to do a lot of uptempo [songs]." The same year, Rihanna dismissed her innocent image for an edgier look with a new hairstyle, which was inspired by actress Charlize Theron's bob cut in the 2005 science fiction thriller Æon Flux.

Rihanna explained that she wanted to keep the audience dancing and be soulful at the same time. She sought to make an album that people would listen to without skipping tracks. She cited Afrodisiac (2004), the fourth studio album by American singer Brandy Norwood, as her main inspiration for the album. In May 2007, Rihanna revealed that she called the album Good Girl Gone Bad because it represents her bolder and more independent image: "I'm not the innocent Rihanna anymore. I'm taking a lot more risks and chances. I felt when I cut my hair, it shows people I'm not trying to look or be anybody else. The album is very edgy."

Recording and production

Good Girl Gone Bad was recorded in Westlake Recording Studios and Conway Studios in Los Angeles, Battery Studios and Roc the Mic Studios in New York City, Chicago Recording Company and Pressure Studios in Chicago, Phase One Audio Group in Toronto, Lethal Studios in Bridgetown, Barbados, Espionage Studios in Oslo and Parr Street Studios in Liverpool. Rihanna spent the week of the 2007 Grammy Awards working with American R&B singer-songwriter Ne-Yo, who gave her vocal lessons. They wrote and sang "Hate That I Love You", which was co-written and produced by Norwegian duo StarGate. Ne-Yo told Vibe magazine, "The best way to express an emotion like love is through storytelling. It makes it more 'I can relate to this character in this song, because I've been through something similar.' You hear that kind of storytelling in the song that I wrote for Rihanna called 'Hate That I Love You'."

American producers Tricky Stewart and Dream had written the track "Umbrella" in 2007 with pop singer Britney Spears in mind. Her label rejected the song before she could hear it, stating they had enough songs for her to record; at the time, Spears was working on her fifth studio album Blackout. The producers then reached out to Mary J. Blige, who did not have time to consider the song for her next album. Finally, L.A. Reid, then-CEO of Def Jam Recordings, bought the record and forwarded it to Rihanna. Initially, Stewart was unsure whether Rihanna was the right artist for the song, but after they had recorded the "ella, ella" catch phrase for the track, he felt optimistic. Rapper Jay Z added rap vocals. Stewart also co-wrote and produced "Breakin' Dishes" with Nash.

"Rehab", "Sell Me Candy", and "Lemme Get That" were composed and produced by Timbaland for the album. He was on the FutureSex/LoveShow concert tour with Justin Timberlake to promote Timberlake's 2006 album FutureSex/LoveSounds. After a show in Chicago, they joined Rihanna in the studio, where Timberlake experimented with beats and melodies. Weeks later, the three met in New York City, where Timberlake had conceptualized a song for Rihanna. Timbaland, who penned a song for Rihanna under the title "Rehab", was producing a beat, over which Timberlake improvised his lyrics. Hannon Lane also co-wrote and co-produced the song. Timberlake told Entertainment Weekly that he believed "Rehab" to be "the bridge for [Rihanna] to be accepted as an adult in the music industry". Rihanna told Robert Copsey of Digital Spy that she enjoyed working with Timberlake, and learned much from the sessions.

Composition

A dance-pop and pop/R&B album influenced by 1980s music, Good Girl Gone Bad is a departure from the Caribbean sound of Rihanna's previous two records. Lyrically, the album is close to some teen pop records, "where sexual-ism and consumerism supersede personal connection."

The LP opens with the lead single "Umbrella", an R&B song performed with drums and thundercloud synths. Dorian Lynskey of The Guardian compared the singer's vocals to the voices of Ciara and Cassie. The second track, "Push Up On Me", features echo electro claps and surging synths. "Don't Stop the Music" is a dance-pop and techno song that contains rhythmic devices used mainly in hip hop music. The song samples the line "Mama-say, mama-sa, ma-ma-ko-ssa" from Michael Jackson's 1983 single "Wanna Be Startin' Somethin'". The fourth song is "Breakin' Dishes"; Peter Robinson of The Observer called it a "wronged-woman bonanza, packed with hooks, chants and flashes of lyrical brilliance." "Shut Up and Drive" is a new wave and pop rock song, influenced by 1970s and 1980s musical styles, sampling New Order's 1983 single "Blue Monday". The collaboration with Ne-Yo, "Hate That I Love You", is a folky R&B song; Nick Levine of Digital Spy compared it to Ne-Yo's sing les "Sexy Love" and "Because of You".

The seventh track on the album, "Say It", samples the 1990s song "Flex" by Mad Cobra; it consists of silky and warm groove and features island-oriented music characteristics. "Sell Me Candy" features jumbled and noisy production with chaotic beats. The ninth song, "Lemme Get That", has boom-bap beats and is produced by Timbaland. "Rehab" is an old-styled R&B track with a groove that is built around tambourine shakes, acoustic guitar swirls and a subtle backbeat. Doug Rule of Metro Weekly noted similarities among the structures of "Rehab" and Timberlake's 2002 single "Cry Me a River". "Question Existing" is an "eerie, smoky, destitute, emotional, and a sonic sidestep." Tom Breihan of Pitchfork Media described the opening lyrics of the song as inspired by "puerile psuedoporn". The album concludes with the title track "Good Girl Gone Bad", which is played with an acoustic guitar and click tracks.

Singles

Released as the lead single from Good Girl Gone Bad, "Umbrella" was sent to contemporary hit, rhythmic and urban radio in the US on April 24, 2007. The song received acclaim from music critics, who praised its production, vocals and the collaboration between Rihanna and Jay Z. "Umbrella" reached number one in more than seventeen countries worldwide, including on the UK Singles Chart and the US Billboard Hot 100 chart. In the United Kingdom, the song topped the singles chart for ten consecutive weeks, while in the United States, it was at the top for seven consecutive weeks. As of June 2013, "Umbrella" has sold 4,236,000 digital copies there, making it Rihanna's fifth-best selling single in the country. Director Chris Applebaum shot the accompanying music video, which features scenes of Rihanna nude and covered in silver paint. The video earned the singer nominations at the 2007 MTV Video Music Awards for Best Direction, Video of the Year and Monster Single of the Yea r; it won the latter two.

The second single from the album, "Shut Up and Drive", was serviced to contemporary hit radio in the US on May 13 and rhythmic radio the following week. The song received mixed response from critics: some praised the composition, while others criticized the lyrics. It reached the top ten on more than twelve national charts, including number five on the UK Singles Chart and number 15 on the US Billboard Hot 100. The music video for the song was shot by Anthony Mandler in Prague, the Czech Republic. The third single, "Hate That I Love You", which features Ne-Yo, was sent to contemporary hit, rhythmic and urban radio in the United States on August 21. Critics gave the song positive reviews and praised the collaboration between the singers; they compared it to the previous works written by Ne-Yo, including the song "Irreplaceable" by Beyoncé. "Hate That I Love You" reached number seven on the US Billboard Hot 100 and number 15 on the UK Singles Chart.

"Don't Stop the Music" was digitally released as an EP via the iTunes Store on September 7. The song received positive reviews from music critics, who praised its production and the interpolation of the "Mama-say, mama-sa, ma-ma-ko-ssa" hook. "Don't Stop the Music" won Best International Song at the 2008 NRJ Music Awards. The single peaked atop of the singles charts in eight countries, reaching number three on the Hot 100 and number four on the UK Singles Chart. It is the seventh-best selling single by Rihanna in the United States, with 3,521,000 digital copies sold as of June 2013. Mandler shot the music video in a nightclub in Prague, the Czech Republic. "Rehab" was released as the fifth and final single from Good Girl Gone Bad; it was sent to contemporary hit radio in the United States on October 6, 2008. Critics were divided on the song's production and composition, and some compared its structure to that of Timberlake's 2007 single "What Goes Around... Comes Around". It reached number 16 on the UK Singles Chart and number 18 on the US Billboard Hot 100 chart. Anthony Mandler directed the accompanying music video, which was shot in Vasquez Rocks Park, near Los Angeles. Timberlake also appears in the video.

Marketing

Release

Good Girl Gone Bad was first released by the Universal Music Group on CD in Portugal on May 31, 2007. It was released in the Netherlands and in Poland the following day. The album was launched in Finland and the United Kingdom on June 4 and in the United States the following day on CD and LP. Good Girl Gone Bad was released on CD in Germany on June 8, on LP in Australia on June 12 and on CD in New Zealand on the same date. A deluxe edition of the album, featuring a bonus disc with dance remixes, was launched on June 27 in Japan.

In early 2008, Rihanna unveiled a new song, "Take a Bow", on the KIIS-FM radio show On Air with Ryan Seacrest. MTV News reported that the track would serve as the lead single from Good Girl Gone Bad: Reloaded, a reissue of the original album to mark its first anniversary. Rihanna further announced that the expanded album would contain another two songs, "Disturbia" and the duet with American pop rock band Maroon 5, titled "If I Never See Your Face Again" to supplement the original track listing. Among other achieved awards and nominations, "Disturbia" and "If I Never See Your Face Again" received nominations for Best Dance Recording and Pop Collaboration with Vocals respectively at the 2009 Grammy Awards.

Good Girl Gone Bad: The Remixes was released on January 27, 2009, and contains club remixes of tracks from the original album and the re-issue. The songs were remixed by producers and disc jockeys such as Moto Blanco, Tony Moran, Soul Seekerz and Wideboys. Good Girl Gone Bad: The Remixes peaked at number 106 on the Billboard 200 and number four on the US Billboard Dance/Electronic Albums chart. As of July 2010, it sold 49,000 copies in the United States.

Live performances

Rihanna performed "Umbrella" with "Shut Up and Drive" and "Breakin' Dishes" at BBC Radio 1's Big Weekend on May 21, 2007. She performed "Umbrella" with Jay Z at the 2007 MTV Movie Awards at the Gibson Amphitheatre, Universal City, California, on June 3. A reviewer of Rap-Up wrote, "she looked hot and the production was on point" during the performance. She performed the song at the Tonight Show with Jay Leno on June 5 and on June 16 at The View. Rihanna performed "Shut Up and Drive" at the 2007 MTV Video Music Awards at The Palms in Las Vegas, and was joined by American rock band Fall Out Boy. In early October 2007, Rihanna was the guest star at the Late Show with David Letterman, where she gave a performance of "Shut Up and Drive". On November 18, Rihanna performed a medley consisting of "Umbrella" and "Hate That I Love You" at the 2007 American Music Awards at the Nokia Theater in Los Angeles, California. Ne-Yo accompanied her for the performance of " Hate That I Love You".

Rihanna performed "Don't Stop the Music" at the 2008 NRJ Music Awards in Cannes, France, on January 26, 2008. She also performed the song at the 50th Grammy Awards on February 10 in a medley with "Umbrella". For the performance, she was joined by American funk band, The Time. On April 28, 2008, Rihanna performed at the Pepsi Center with Kanye West, N.E.R.D and Lupe Fiasco. She sang "Rehab", "Hate That I Love You", "Don't Stop the Music" and "Umbrella". On June 20, she was a guest on NBC's Today Concert Series in Rockefeller Center, New York City. She performed "Don't Stop the Music", "Umbrella" and "Take a Bow". She also performed "Rehab" live on November 23, 2008, at the 2008 American Music Awards, where she won the awards for Favorite Pop/Rock Female Artist and Favorite Soul/R&B Female Artist. At the awards ceremony, she performed wearing an eye patch, which she removed after she was lowered to the main stage.

Tour

To further promote the album, Rihanna embarked on her first worldwide and second overall tour, the Good Girl Gone Bad Tour (2007â€"09). She performed in Europe, North America, Oceania, Asia and Africa. During the concert shows she wore S&M-inspired outfits and high boots. Mike Usinger of The Georgia Straight gave the show a mixed review; he wrote that even though Rihanna's vocals were improved, he felt she still struggled to keep the audience engaged. Jason MacNeil of Canadian Online Explorer gave a positive review of the concert after the show at Molson Amphitheatre, saying "the singer made a rather eye-popping impression, opening with 'Pon de Replay' and clad in a sexy, dominatrix-like studded black leather ensemble." During a show planned for February 13 in Malaysia, Malaysia's conservative Islamic party recommended that Rihanna's concert tour be banned from performing, citing her outfits. A video album, Good Girl Gone Bad Live, was filmed at the Manchester Ar ena show in Manchester, United Kingdom, on December 6, 2007. The Good Girl Gone Bad Live DVD was released on June 9 and 13, 2008, in the United Kingdom and Germany through Mercury Records and the Universal Music Group respectively.

Critical reception

Good Girl Gone Bad received generally favorable reviews from music critics. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 72 based on 16 reviews. Uncut called it a "shiny, trans-atlantic blend of Europop vim, R&B grit and Caribbean bounce." Andy Kellman of AllMusic deemed it quintessential pop music and said each of its tracks was a potential hit. Quentin B. Huff of PopMatters praised the album, describing it as "more raw, perhaps edgier and more risqué" than Rihanna's previous material. Kelefa Sanneh of The New York Times wrote that the album "sounds as if it were scientifically engineered to deliver hits". Peter Robinson of The Observer commended her collaborators for "masking her own shortcomings" and commented that, "While Rihanna lacks her peers' charisma, she's a great vessel for exhilarating mainstream pop." Pitchfork Media's Tom Breihan found the album varied and satisfying. Neil Drumming of Entertainment Weekly felt that, although it "goes bad when Rihanna tries her hand at treacly ballads and glum sentiment", at times Good Girl Gone Bad is a "thrilling throwback to more than a decade ago, when upstart producers haphazardly mashed R&B with hip-hop to create chunky jeep anthems such as Mary J. Blige's 'Real Love'."

In a mixed review, Rodney Dugue of The Village Voice felt that the album "never settles on a sound" and only cited its three Timbaland-produced songs as highlights. Although he found the ballads to be improvements from Rihanna's previous albums, Slant Magazine's Sal Cinquemani criticized the lyrics, particularly those written by Justin Timberlake, as an "Achilles' high heel for Rihanna". Alex Macpherson of The Guardian found Rihanna to be "ill-suited" for its dance-pop songs and stated, "The gimmicky samples and pounding beats bury her personality, and the summery reggae of her first two albums is sorely missed." Robert Christgau of MSN Music cited "Umbrella" as a "choice cut", indicating "a good song on an album that isn't worth your time or money".

Commercial performance

In the United States, Good Girl Gone Bad debuted at number two on the Billboard 200 chart, selling 162,000 copies in its first week. It became Rihanna's then-best start album entry. The next week, it fell to number seven with 81,000 copies sold. The re-issue sold 63,000 copies in the first week and helped Good Girl Gone Bad jump from number 124 to number seven on the US Billboard 200 in its 55th week. It was certified quintuple platinum by the Recording Industry Association of America (RIAA); by November 2013, both Good Girl Gone Bad and the reissue had sold 2,800,000 copies in the United States alone. To date, it is her best-selling album in the former country. The album debuted atop of the Canadian Albums Chart and became Rihanna's second number-one album in the country. It was certified quintuple platinum by Music Canada, denoting shipments of more than 500,000 copies.

Good Girl Gone Bad debuted at number one on the UK Albums Chart. It became her first album to top the chart, and stayed on the chart for 177 weeks. In 2011, the album peaked at number 16 on the UK R&B Albums Chart. It was certified sextuple platinum by the British Phonographic Industry (BPI) and sold over 1,850,000 copies in the country. It ended at number 10 on the UK 2007 year-end list and number six on the 2008 year-end list. As of March 2015, Good Girl Gone Bad is the 46th best-selling album of the millennium in the United Kingdom. In Ireland, Good Girl Gone Bad debuted at number three on the Irish Singles Chart on June 7, 2007. After four weeks on the chart, it reached the top. The album peaked at number one on the Swiss Hitparade chart and stayed on the chart for 91 weeks. In Australia, it peaked at number two and was certified triple platinum by the Australian Recording Industry Association (ARIA), denoting shipments of over 210,000 copies. The albu m had sold 7 million copies worldwide.

Before its physical release, "Umbrella" achieved the biggest debut in the six-year history of the iTunes Store in the United States, breaking a record previously held by the 2006 single "Hips Don't Lie". Following its digital release, the song debuted atop the Hot Digital Songs chart, with first-week sales of more than 277,000 units. The single became the highest digital debut in the United States since Nielsen SoundScan began tracking downloads in 2003, surpassing Timberlake's "SexyBack" 250,000 sales record in 2006.

Accolades

At the 2008 Grammy Awards ceremony, Good Girl Gone Bad received seven Grammy Awards nominations, including Record of the Year and Song of the Year for "Umbrella", Best Dance Recording for "Don't Stop the Music", Best R&B Performance by a Duo or Group with Vocals and Best R&B Song for "Hate That I Love You". It won the accolade for Best Rap/Sung Collaboration for "Umbrella". Additionally, magazine Rolling Stone placed "Umbrella" at number 412 on their 500 Greatest Songs of All Time list. The album also won the International Album of the Year award at the 2008 Juno Awards.

Legacy

According to Biography.com, Good Girl Gone Bad inspired Rihanna to transform her image from a "teen pop princess" persona into a "fully fledged superstar and sex symbol". People magazine noted that Rihanna follows the likes of recording artists Janet Jackson and Christina Aguilera "when she sheds her innocent image for an edgier look and sound". Jay-Z also spoke about "Umbrella" and stated that the song represents an artistic grow for Rihanna, "If you listen to the lyrics to that song, you know the depth and how far she's come." Regarding the commercial impact of the album, Entertainment Weekly's Margeaux Watson wrote, "For a pop star who was once dismissed as being incapable of yielding more than one hit song per album, Rihanna's newfound staying power is nothing short of remarkableâ€"and proof that there's room for more than one diva in this game." Jason Birchmeier of AllMusic concluded that it was Good Girl Gone Bad that made Rihanna a "full-fledged international pop star with a regular presence atop the charts". Nick Levine of Digital Spy described the album, as the closest thing to a Thriller that 2007/08 is likely to produce.

Track listing

Notes

• ^{^a} denotes a vocal producer
• ^{^b} denotes a co-producer
• ^{^c} denotes a remixer and additional producer
• "Push Up on Me" samples "Running with the Night", as written by Lionel Richie and Cynthia Weil, and performed by Richie.
• "Don't Stop the Music" samples "Wanna Be Startin' Somethin'", as written and performed by Michael Jackson, which itself samples "Soul Makossa", as performed by Manu Dibango.
• "Shut Up and Drive" samples "Blue Monday", as written and performed by New Order (Stephen Morris, Peter Hook, Bernard Sumner and Gillian Gilbert).
• "Say It" samples "Flex", as written by Ewart Brown, Clifton Dillon, Sly Dunbar and Brian Thompson, and performed by Mad Cobra.

Personnel

Credits for Good Girl Gone Bad adapted from AllMusic.

Charts

Certifications

Release history

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The Champagne wine region (archaic English: Champany) is a wine region within the historical province of Champagne in the northeast of France. The area is best known for the production of the sparkling white wine that bears the region's name. EU law and the laws of most countries reserve the term "Champagne" exclusively for wines that come from this region located about 100 miles (160 km) east of Paris. The viticultural boundaries of Champagne are legally defined and split into five wine producing districts within the historical province: Aube, Côte des Blancs, Côte de Sézanne, Montagne de Reims, and Vallée de la Marne. The towns of Reims and Épernay are the commercial centers of the area.

Located at the northern edges of France, the history of the Champagne wine region has had a significant role in the development of this unique terroir. The area's proximity to Paris promoted the region's economic success in its wine trade but also put the villages and vineyards in the path of marching armies on their way to the French capital. Despite the frequency of these military conflicts, the region developed a reputation for quality wine production in the early Middle Ages and was able to continue that reputation as the region's producers began making sparkling wine with the advent of the great Champagne houses in the 17th and 18th centuries. The principal grapes grown in the region include Chardonnay, Pinot noir, and Pinot Meunier. Pinot noir is the most widely planted grape in the Aube region and grows very well in Montagne de Reims. Pinot Meunier is the dominant grape in the Vallée de la Marne region. The Côte des Blancs is dedicated almost exclusively to Chardonnay.

Geography and climate

The Champagne province is located near the northern limits of the wine world along the 49th parallel. The high altitude and mean annual temperature of 10 °C (50 °F) creates a difficult environment for wine grapes to fully ripen. Ripening is aided by the presence of forests which helps to stabilize temperatures and maintain moisture in the soil. The cool temperatures serve to produce high levels of acidity in the resulting grape which is ideal for sparkling wine.

During the growing season, the mean July temperature is 18 °C (66 °F). The average annual rainfall is 630 mm (25 inches), with 45 mm (1.8 inches) falling during the harvest month of September. Throughout the year, growers must be mindful of the hazards of fungal disease and early spring frost.

Ancient oceans left behind chalk subsoil deposits when they receded 70 million years ago. Earthquakes that rocked the region over 10 million years ago pushed the marine sediments of belemnite fossils up to the surface to create the belemnite chalk terrain. The belemnite in the soil allows it to absorb heat from the sun and gradually release it during the night as well as providing good drainage. This soil contributes to the lightness and finesse that is characteristic of Champagne wine. The Aube area is an exception with predominately clay based soil. The chalk is also used in the construction of underground cellars that can keep the wines cool through the bottle maturation process.

History

The Carolingian reign saw periods of prosperity for the Champagne region beginning with Charlemagne's encouragement for the area to start planting vines and continuing with the coronation of his son Louis the Pious at Reims. The tradition of crowning kings at Reims contributed to the reputation of the wines that came from this area. The Counts of Champagne ruled the area as an independent county from 950 to 1316. In 1314, the last Count of Champagne assumed the throne as King Louis X of France and the region became part of the Crown territories.

Military conflicts

The location of Champagne played a large role in its historical prominence as it served as a "crossroads" for both military and trade routes. This also made the area open to devastation and destruction during military conflicts that were frequently waged in the area. In 451 A.D. near Châlons-en-Champagne Attila and the Huns were defeated by an alliance of Roman legions, Franks and Visigoths. This defeat was a turning point in the Huns' invasion of Europe.

During the Hundred Years' War, the land was repeatedly ravaged and devastated by battles. The Abbey of Hautvillers, including its vineyards, was destroyed in 1560 during the War of Religion between the Huguenots and Catholics. This was followed by conflicts during the Thirty Year War and the Fronde Civil War where soldiers and mercenaries held the area in occupation. It was not until the 1660s, during the reign of Louis XIV, that the region saw enough peace to allow advances in sparkling wine production to take place.

History of wine production

The region's reputation for wine production dates back to the Middle Ages when Pope Urban II, a native Champenois, declared that the wine of Aÿ in the Marne département was the best wine produced in the world. For a time Aÿ was used as a shorthand designation for wines from the entire Champagne region, similar to the use of Beaune for the wines of Burgundy. The poet Henry d'Andeli's work La Bataille des Vins rated wines from the towns of Épernay, Hautvillers and Reims as some of the best in Europe. As the region's reputation grew, popes and royalty sought to own pieces of the land with Pope Leo X, Francis I of France, Charles V of Spain, and Henry VIII of England all owning vineyard land in the region. A batch of wine from Aÿ received in 1518 by Henry VIII's chancellor, Cardinal Thomas Wolsey, is the first recorded export of wine from the Champagne region to England.

The still wines of the area were highly prized in Paris under the designation of vins de la rivière and vins de la montagne- wines of the river and wines of the mountain in reference to the wooded terrain and the river Marne which carried the wines down to the Seine and into Paris. The region was in competition with Burgundy for the Flemish wine trade and tried to capitalize on Reims' location along the trade route from Beaune. In the 15th century, Pinot noir became heavily planted in the area. The resulting red wine had difficulty comparing well to the richness and coloring of Burgundy wines, despite the addition of elderberries to deepen the color. This led to a greater focus on white wines.

The Champagne house of Gosset was founded as a still wine producer in 1584 and is the oldest Champagne house still in operation today. Ruinart was founded in 1729 and was soon followed by Chanoine Frères (1730), Taittinger (1734), Moët et Chandon (1743) and Veuve Clicquot (1772).

The nineteenth century saw an explosive growth in Champagne production going from a regional production of 300,000 bottles a year in 1800 to 20 million bottles in 1850.

Rivalry with Burgundy

A strong influence on Champagne wine production was the centuries-old rivalry between the region and Burgundy. From the key market of Paris to the palace of Louis XIV of France at Versailles, proponents of Champagne and Burgundy would compete for dominance. For most of his life, Louis XIV would drink only Champagne wine with the support of his doctor Antoine d'Aquin who advocated the King drink Champagne with every meal for the benefit of his health. As the King aged and his ailments increased, competing doctors would propose alternative treatments with alternative wines, to soothe the King's ills. One of these doctors, Guy-Crescent Fagon conspired with the King's mistress to oust d'Aquin and have himself appointed as Royal Doctor. Fagon quickly attributed the King's continuing ailments to Champagne and ordered that only Burgundy wine must be served at the royal table.

This development had a ripple effect throughout both regions and in the Paris markets. Both Champagne and Burgundy were deeply concerned with the "healthiness" reputation of their wines, even to the extent of paying medical students to write theses touting the health benefit of their wines. These theses were then used as advertising pamphlets that were sent to merchants and customers. The Faculty of Medicine in Reims published several papers to refute Fagon's claim that Burgundy wine was healthier than Champagne. In response, Burgundian winemakers hired physician Jean-Baptiste de Salins, dean of the medical school in Beaune, to speak to a packed auditorium at the Paris Faculty of Medicine. Salins spoke favorably of Burgundy wine's deep color and robust nature and compared it to the pale red color of Champagne and the "instability" of the wine to travel long distances and the flaws of the bubbles from when secondary fermentation would take place. The text of his spe ech was published in newspapers and pamphlets throughout France and had a damaging effect on Champagne sales.

The war of words would continue for another 130 years with endless commentary from doctors, poets, playwrights and authors all arguing for their favorite region and their polemics being reproduced in advertisements for Burgundy and Champagne. On a few occasions, the two regions were on the brink of civil war. A turning point occurred when several Champagne wine makers abandoned efforts to produce red wine in favor of focusing on harnessing the effervescent nature of sparkling Champagne. As the bubbles became more popular, doctors throughout France and Europe commented on the health benefits of the sparkling bubbles which were said to cure malaria. As more Champenois winemakers embarked on this new and completely different wine style, the rivalry with Burgundy mellowed and eventually waned.

Classifications and vineyard regulations

In 1927, viticultural boundaries of Champagne were legally defined and split into five wine producing districts- The Aube, Côte des Blancs, Côte de Sézanne, Montagne de Reims, and Vallée de la Marne. This area covers 33,500 hectares (76,000 acres) of vineyards around 319 villages that are home to 5,000 growers who make their own wine and 14,000 growers who only sell grapes. The region is set to expand to include 359 villages in the near future.

The different districts produce grapes of varying characteristics that are blended by the Champagne houses to create their distinct house styles. The Pinots of the Montagne de Reims that are planted on northern facing slopes are known for their high levels of acid and the delicacy they add to the blend. The grapes on the southern facing slope add more power and character. Grapes across the district contribute to the bouquet and headiness. The abundance of southern facing slopes in the Vallée de la Marne produces the ripest wines with full aroma. The Côte des Blancs grapes are known for their finesse and the freshness they add to blends with the extension of the nearby Côte de Sézanne offering similar though slightly less distinguished traits.

In 1942, the Comité Interprofessionnel du Vin de Champagne (CIVC) was formed with the purpose of protecting Champagne's reputation and marketing forces as well as setting up and monitoring regulations for vineyard production and vinification methods. Champagne is the only region that is permitted to exclude AOC or Appellation d'Origine Contrôlée from their labels.

For each vintage, the CIVC rated the villages of the area based on the quality of their grapes and vineyards. The rating was then used to determine the price and the percentage of the price that growers get. The Grand Cru rated vineyards received 100 percent rating which entitled the grower to 100% of the price. Premier Crus were vineyards with 90â€"99% ratings while Deuxième Crus received 80â€"89% ratings. Under appellation rules, around 4,000 kilograms (8,800 pounds) of grapes can be pressed to create up to 673 gallons (either 2,550 L or 3,060 L) of juice. The first 541 gallons (either 2,050 L or 2,460 L) are the cuvée and the next 132 gallons (either 500 L or 600 L) are the taille. Prior to 1992, a second taille of 44 gallons (either 167 L or 200 L) was previously allowed. For vintage Champagne, 100% of the grapes must come from that vintage year while non-vintage wine is a blend of vintages. Vintage champagne must spend a minimum of three years of aging. There are no regulations about how long it must spend on its lees, but some of the premier Champagne houses keep their wines on lees for upwards of five to ten years. Non-vintage Champagne must spend a minimum of 15 months of aging but only a minimum of 12 months on the lees. Most of the Champagne houses keep their wines on the lees through the whole time of aging because it is more expense to bottle the wine then age it and finally shipped.

Revision of the Champagne region

The worldwide demand for Champagne has been continuously increasing throughout the 1990s and early 2000s. A record in worldwide shipping of Champagne (including domestic French consumption) of 327 million bottles was set in 1999 in anticipation of end of millennium celebrations, and a new record was set in 2007 at 338.7 million bottles. Since the entire vineyard area authorized by the 1927 AOC regulations is now planted, various ways of expanding the production have been considered. The allowed yield was increased (to a maximum of 15,500 kg per hectare during an experimental period from 2007 to 2011) and the possibility of revising the production region was investigated.

After an extensive review of vineyard conditions in and around the existing Champagne region, INAO presented a proposal to revise the region on March 14, 2008. The proposal was prepared by a group of five experts in the subjects of history, geography, geology, phytosociology and agronomy, working from 2005. The proposal means expanding the region to cover vineyards in 357 rather than 319 villages. This is to be achieved by adding vineyards in forty villages while simultaneously removing two villages in the Marne départment that were included in the 1927 regulations, Germaine and Orbais-l'Abbaye.

The proposed 40 new Champagne villages are located in four départments:

• 22 in Marne: Baslieux-les-Fismes, Blacy, Boissy-le-Repos, Bouvancourt, Breuil-sur-Vesle, Bussy-le-Repos, Champfleury, Courlandon, Courcy, Courdemanges, Fismes, Huiron, La Ville-sous-Orbais, Le Thoult-Trosnay, Loivre, Montmirail, Mont-sur-Courville, Peas, Romain, Saint-Loup, Soulanges, and Ventelay.
• 15 in Aube: Arrelles, Balnot-la-Grange, Bossancourt, Bouilly, Étourvy, Fontvannes, Javernant, Laines-aux-Bois, Macey, Messon, Prugny, Saint-Germain-l'Épine, Souligny, Torvilliers and Villery.
• Two in Haute-Marne: Champcourt and Harricourt.
• One, Marchais-en-Brie, in Aisne.

The INAO proposal was to be subject to review before being made into law and was immediately questioned in numerous public comments. The mayor of one the villages to be delisted, Germaine, immediately appealed against INAO's proposal, with the possibility of additional appeals by vineyard owners. The initial review process is expected to be finished by early 2009. This will be followed by another review of the specific parcels that will be added or deleted from the appellation. The earliest vineyard plantings are expected around 2015, with their product being marketed from around 2021. However, the price of land that are allowed to be used for Champagne production is expected to immediately rise from 5,000 to one million euro per hectare.

While some critics have feared the revision of the Champagne region is about expanding production irrespective of quality, British wine writer and Champagne expert Tom Stevenson has pointed out that the proposed additions constitute a consolidation rather than expansion. The villages under discussion are situated in gaps inside the perimeter of the existing Champagne regions rather than outside it.

Production other than sparkling wine

While totally dominating the region's production, sparkling Champagne is not the only product that is made from the region's grapes. Non-sparkling still wines, like those made around the village Bouzy, are sold under the appellation label Coteaux Champenois. There is also a rosé appellation in the region, Rosé des Riceys. The regional vin de liqueur is called Ratafia de Champagne. Since the profit of making sparkling Champagne from the region's grape is now much higher, production of these non-sparkling wines and fortified wines is very small.

The pomace from the grape pressing is used to make Marc de Champagne, and in this case the production does not compete with that of Champagne, since the pomace is a by-product of wine production.

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Field & Stream is a retailer of hunting, fishing, camping, and related outdoor recreation merchandise that is a subsidiary of Dick's Sporting Goods.

History

On August 16, 2013, Dick's Sporting Goods opened its first Field & Stream Shop in Cranberry Township, Pennsylvania, at the site of the former Dick's location in Cranberry (Dick's had moved to a newer location nearby in Cranberry Township in 2012), operating as a competitor to Cabela's. Willie Robertson of the reality television series Duck Dynasty made a speaking appearance at a wedding at the store, with both participants dressed in camouflage, as well as retired WWE wrestler Shawn Michaels (currently hosting MacMillan River Adventures on the Outdoor Channel) appearing at the store to sign autographs for the grand opening. Later in the month, the store began selling AR-15 semi-automatic rifles, ending the chain's 2012 self-imposed suspension of sales of certain semi-automatic firearms following the Sandy Hook Elementary School shooting.

The first locations opened after the Cranberry store were in Erie, Pennsylvania (on the site of a proposed Cabela's store that Dick's had purchased before Cabela's had a chance to buy it), Altoona, Pennsylvania, and Crescent Springs, Kentucky. On October 10, 2014, a newly constructed Field & Stream Shop opened in Miamisburg, Ohio and Horseheads, New York. The Miamisburg store opened its doors on October 8, 2014, although the official opening was not until October 10, 2014.

Field & Stream plans to open 30 to 35 stores by the end of 2017.

References

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A paper plane, paper aeroplane (UK), paper airplane (US), paper glider, paper dart or dart is a toy aircraft, usually a glider made out of folded paper or paperboard.

History

The origin of folded paper gliders is generally considered to be of Ancient China, although there is equal evidence that the refinement and development of folded gliders took place in equal measure in Japan. Certainly, manufacture of paper on a widespread scale took place in China 500 BCE, and origami and paper folding became popular within a century of this period, approximately 460-390 BCE. It is impossible to ascertain where and in what form the first paper aircraft were constructed, or even the first paper plane's form.

For over a thousand years after this, paper aircraft were the dominant man-made heavier-than-air craft whose principles could be readily appreciated, though thanks to their high drag coefficients, not of an exceptional performance when gliding over long distances. The pioneers of powered flight have all studied paper model aircraft in order to design larger machines. Da Vinci wrote of the building of a model plane out of parchment, and of testing some of his early ornithopter, an aircraft that flies by flapping wings, and parachute designs using paper models. Thereafter, Sir George Cayley explored the performance of paper gliders in the late 19th century. Other pioneers, such as Clément Ader, Prof. Charles Langley, and Alberto Santos-Dumont often tested ideas with paper as well as balsa models to confirm (in scale) their theories before putting them into practice.

The most significant use of paper models in aircraft designs were by the Wright brothers between 1899 and 1903, the date of the first powered flight from Kill Devil Hills, by the Wright Flyer. The Wrights used a wind tunnel to gain knowledge of the forces which could be used to control an aircraft in flight. They built numerous paper models, and tested them within their wind tunnel. By observing the forces produced by flexing the heavy paper models within the wind tunnel, the Wrights determined that control through flight surfaces by warping would be most effective, and in action identical to the later hinged aileron and elevator surfaces used today. Their paper models were very important in the process of moving on to progressively larger models, kites, gliders and ultimately on to the powered Flyer (in conjunction with the development of lightweight petrol engines). In this way, the paper model plane remains a very important key in the graduation from model to manned heavier-tha n-air flight.

With time, many other designers have improved and developed the paper model, while using it as a fundamentally useful tool in aircraft design. One of the earliest known applied (as in compound structures and many other aerodynamic refinements) modern paper plane was in 1909.

The construction of a paper airplane, by Ludwig Prandtl at the 1924 banquet of the International Union of Theoretical and Applied Mechanics, was dismissed as an artless exercise by Theodore von Kármán:

Prandtl was also somewhat impulsive. I recall that on one occasion at a rather dignified dinner meeting following a conference in Delft, Holland, my sister, who sat next to him at the table, asked him a question on the mechanics of flight. He started to explain; in the course of it he picked up a paper menu and fashioned a small model airplane, without thinking where he was. It landed on the shirtfront of the French Minister of Education, much to the embarrassment of my sister and others at the banquet.

In 1930 Jack Northrop (co-founder of Lockheed Corporation) used paper planes as test models for larger aircraft. In Germany, during the Great Depression, designers at Heinkel and Junkers used paper models in order to establish basic performance and structural forms in important projects, such as the Heinkel 111 and Junkers 88 tactical bomber programmes.

In recent times, paper model aircraft have gained great sophistication, and very high flight performance far removed from their origami origins, yet even origami aircraft have gained many new and exciting designs over the years, and gained much in terms of flight performance.

There have been many design improvements, including velocity, lift, propulsion, style and fashion, over subsequent years.

Advanced paper gliders

Developments

Paper gliders have experienced three forms of development in the period 1930â€"1988:

• High flight performance
• Scale modeling
• Use of CAD software

Ongoing development of folded/origami gliders over the same period has seen similar sophistication, including the addition of the following construction refinements

• Increased fold-count, sometimes of an intricate nature
• Explicit kirigami (cutting of paper) as a component of design
• Requirements for additional ballast to ensure flight performance

Technological introductions

Technology responsible for the proliferation of advanced paper plane construction:

• Inexpensive CAD software for 2D part design
• Widespread manufacture, and inexpensive nature of acetal air-annealed glues, e.g. Bostick Clear-bond.
• Inexpensive ink and laser computer printers, for accurate aircraft part reproduction
• The advent of the Internet, and widespread information sharing

Material considerations

Compared to balsa wood, another material commonly used to fabricate model planes, paper's density is higher; consequentially, conventional origami paper gliders (see above) suffer from higher drag, as well as imperfectly aerodynamic wing chords.

However, unlike balsa gliders, paper gliders have a far higher strength-to-thickness ratio â€" a sheet of office-quality 80 g/sq m photocopier/laser printer paper, for example, has approximate in-scale strength of aircraft-grade aluminium sheet metal, while card stock approximates the properties of steel at the scale of paper model aircraft.

Directions in advanced paper aircraft design

Unmodified origami paper aircraft have very poor glide ratios, often not better than 7.5:1 depending on construction and materials. Modification of origami paper gliders can lead to marked improvements in flight performance, at the cost of weight and often with the inclusion of aerodynamic and/or structural compromises. Often, increases in wing loading can encourage breakdown of laminar flow over a wing with a hybrid of origami and glued and taped construction.

Professors Ninomiya and Mathews (see sections below) developed more directed design strategies in the late 1960s and the 1980s. Previously, paper model aircraft had been designed without an emphasis on performance in flight. By using aerodynamic design, and fluid dynamics, both professors were able to design models that exceeded previous flight performance criteria by a very wide margin. Ranges of flight increased from the typical 10+ meters to 85+ meters, depending on energy input into the gliders on launch.

At present, the work of the two professors remains the last serious research work on improving the flight performance of paper model gliders. Collaborative work by enthusiasts through online forums and personal websites are mostly developments of these original glider types.

In the field of scale model design, there are at present many possibilities for advanced design. Profile gliders encounter a limitation for improvement of flight performance based on their wing types, which are typically curved-plate aerofoils. In addition, fuselages are either balsa-paper or paper laminates, prone to warping or breakage over a very short time. Improvement in performance is possible through modelling three-dimensional fuselages which encourage laminar flow, and in internally braced wings which can then have high-lift aerofoil profiles, such as the Clark Y or NACA 4 or 6 series, for high lift.

White Wings

In Japan in the late 1960s, Professor Yasuaki Ninomiya designed an advanced type of paper aircraft, which were published in two books, Jet Age Jamboree (1966) and Airborne All-Stars (1967). Designs from these books were later sold as the 'White Wings' Series of paper glider packs from the 1970s to the present day.

White Wings are a stark departure from conventional paper aircraft, in that their fuselages and wings are paper templates cut and glued together. They were designed with the aid of low-speed aerodynamic engineering design principles. Construction of the models is of Kent paper, a grade of cartridge paper sold in Japan.

The early models were explicitly hand drawn, but by the 1980s these had their parts drafted with the use of CAD software.

Seen below is the N-424 glider from Jet Age Jamboree (1966) The glider fuselage is constructed from several laminations of paper glued together. The wings are of two laminations, and the tailplane and tailfin of a single lamination.

Prof. Ninomiya's designs also included, for the first time in any paper model, working propellers driven by airflow, in particular for his profile scale models of the Cessna Skymaster and Piaggio P.136 of 1967. Noteworthy as well was the careful design of gliders so that they could fly without ballast â€" his F-4 Phantom II model is able to be flown immediately without recourse to paperclips etc.

The high performance gliders have fuselages that are kept rigid by the use of a balsa fuselage profile bonded to the paper components. The paper used is quite heavy, approximately twice the weight of standard drawing cartridge paper, but lighter than lightweight cardboard. Original White Wings were entirely paper, requiring patience and skill. Later however, balsa-wood fuselages were used, and White Wings were sold "pre-cut", making construction easier. The aerofoil used is a Göttingen 801 (curved plate), and a pattern is supplied as a cutout part of each kit.

Paper Pilot

History

In 1984, Professor E.H. Mathews, lecturer in Thermodynamics at the University of the Wiwatersrand, South Africa published his first compendium of high-performance model aircraft. This book was Paper Pilot (Struik, 1984).

This book was very successful, leading to additional volumes, Paper Pilot 2 (1988), Paper Pilot 3 (1991), 12 Planes for the Paper Pilot (1993) and Ju-52, a stand-alone book featuring a scale model.

Unpublished models include an Airbus A320 scale model much like the Ju-52, seen on the Tekkies youth program in 1996.

The books featured patterns of parts printed on lightweight cardstock, to give the aircraft good flight penetration performance for long distance flight.

Design and development

Public interest in the gliders, and their publishing success, allowed some of the development to be broadcast on South African television during 1988 on the first book's release, and again 1993, to coincide with a national paper aeroplane competition tied to Paper Pilot 3's release.

Aerodynamic design of the gliders was achieved making use of an optimised small wind tunnel - the flat-glider Britten Norman Trislander was filmed in this facility, with weight balances being used to demonstrate the optimisation of flight.

The design of parts of the gliders was achieved using Autodesk AutoCAD R12, then the most advanced version of this CAD software, and one of the first publicly available paper model aeroplanes designed using this technology.

Construction of the gliders closely parallels that used in the White Wings series of gliders of Dr. Ninomiya for flat gliders.

Later gliders with three-dimensional fuselages use a lightweight construction optimised for flight performance.

Innovations include functional wheeled undercarriage which does not contribute to the drag budget while permitting good landings.

Performance

Paper pilot gliders make use a curved-plate aerofoil shape for best performance. Their design, like the White Wings gliders, is very sensitive to trim, and in fact have the capacity to make indoor flights in confined spaces under average conditions.

Most in initial editions are equipped with catapult hook patterns, and demonstrate an ability to fly the length of a Rugby pitch when so launched.

Later editions and gliders were equipped with a Bungee hook, the construction of which was included in Paper Pilot 3 and 12 Planes for the Paper Pilot.

The Bungee system publish parallels, at a smaller scale, the practice used in radio controlled and full-size sailplane launches, at a fraction of the cost and complexity. To date, this is the only known example of such a launch system applied to a paper model aeroplane type published in book form.

Flight performance on bungee is very good - one glider in particular, a scale model U-2 (in the last book of the series) had demonstrated flight performance in excess of 120 meters, on bungee hook launch.

Papercopter

A unique development of Prof. Mathews is the Papercopter, a model helicopter whose 'wing' is a trimmable annular ring which, using rotational aerodynamics to provide good forward flight performance without need for a tail rotor. A model helicopter 'body' is suspended beneath the ring, and uses airflow to stabilise itself in the direction of flight, much like a weather vane.

The papercopter design permits flights of approximately 10â€"14 meters on average.

Paper helicopters (autogyros)

The world's first known published paper autogyro (engineless helicopter) by Richard K Neu appeared in "The Great International Paper Airplane Book" published in 1967. Its wings fly in a circle around a central ballast shaft as it descends vertically. This basic design has been published several times and is widely known.

The world's first known published forward-gliding paper autogyro with forward-pointing body lifted by spinning blades was built by James Zongker. It appears on page 53 of "The Paper Airplane Book: The Official Book of the Second Great International Paper Airplane Contest" published in 1985 by Science Magazine. Its twin contra-rotating blades automatically spin on paper axles upon launch to provide lift.

As noted above (see entry, Paper Pilot), E.H. Mathews developed a flight-stable paper model helicopter. This has a ring wing, and flaps for adjusting for flight for stability, positioned on the inboard edge of the ring. While not an autogyro per se, this paper model aircraft class falls within the general design of a paper model helicopter, and does possess a rotational flight element producing lift during forward flight. Papercopters, as Professor Mathews labeled them, are unique among paper model rotorcraft in having a range and velocity far in excess of all other classes, able to fly quite quickly, and with a range of between 10â€"15 m. The longest flight time is 27.9 seconds.

World records

There are multiple goals for a flight:

• Distance (javelin throwing).
• Time (javelin throwing straight up with subsequent metamorphosis into a sailplane).
• Aerobatic (looping).
• Stable flight to understand flight mechanics of a good plane.

For every goal there is a typical plane and sometimes a world record.

There have been many attempts over the years to break the barriers of throwing a paper plane for the longest time aloft. Ken Blackburn held this Guinness World Record for 13 years (1983â€"1996) and had regained the record on October 1998 by keeping his paper plane aloft for 27.6 seconds (indoors). This was confirmed by Guinness officials and a CNN report. The paper plane that Blackburn used in this record breaking attempt was a "glider". As of 2012, Takuo Toda holds the world record for the longest time in air (27.9 seconds). The distance record (226 feet 10 inches or 69.14 metres) was set by Joe Ayoob, with a plane constructed by John Collins, in February 2012.

Aerodynamics

General aerodynamics

Paper aircraft are a class of model plane, and so do not experience aerodynamic forces differently from other types of flying model. However, their construction material produces a number of dissimilar effects on flight performance in comparison with aircraft built from different materials.

In general, there are four aerodynamic forces that act on the paper aircraft while it is in flight:

• Thrust, which keeps the plane moving forward;
• Aerodynamic lift, acting on horizontal surface areas that lifts the plane upward;
• Gravity, which counteracts lift and pulls the plane downward; and
• Air drag, which counteracts thrust and reduces the plane's forward speed.

Altogether, the aerodynamic forces co-interact, creating turbulence that amplifies small changes in the surface of the paper aircraft. Modifications can be made to most paper airplanes by bending, curving or making small cuts in the trailing edges of wings and in the airplane's tail, if it has one.

The most common adjustments, modelled after glider aircraft, are ailerons, elevators, and rudders.

Critical Re

The Reynolds number range of the paper model aircraft is reasonably wide:

• 2,000â€"12,000 for Origami aircraft
• 4,000â€"16,900 for Compound Origami (involving adhesives and aerodynamic refinements)
• 9,000â€"39,000 for Profile Performance (White Wings, Paper Pilot, et al.)
• 19,200â€"56,000 for Scale Performance (White Wings, Paper Pilot, et al.)
• 22,000â€"93,000 for Scale Models (complex structures)

These ranges are indicative. As noted above the mass: density ratio of paper prevents performance from reaching those of Balsa models in terms of expressions of power to weight, but for models with wingspans of between 250 mm and 1,200 mm, the Critical Re is very similar to balsa model gliders of similar dimensions.

Paper models typically have a wing aspect ratio that is very high (model sailplanes) or very low (the classic paper dart), and therefore are in almost all cases flying at velocities far below their wing planform and aerofoil Critical Re, where flow would break down from laminar to turbulent.

Most origami paper darts tend to be flying within turbulent air in any case, and as such, are important to research into turbulent flow as are low-Re lifting surfaces found in nature such as leaves of trees and plants as well as the wings of insects.

High performance profile and scale models do approach their wing section's critical Re in flight, which is a noteworthy achievement in terms of paper model design. Performance is derived of the fact that wings of these gliders are in fact performing as well as it is possible for them to perform, given their material limitations.

Experiments in different material finishes in recent years have revealed some interesting relationships in Re and paper models. Performance of origami and compound origami structures improves markedly with the introduction of smooth paper, though this is also aided by the paper's higher mass and consequently better penetration.

More marginal performance and scale types generally do not benefit from heavier, shinier surfaces. Performance profile-fuselage types do experience somewhat improved performance if shiny, slippery paper is used in construction, but although there is a velocity improvement, this is offset very often by a poorer l/d ratio. Scale types have experience negative performance at the addition of heavy shiny papers in their construction.

Aerofoils

Wing profile sections in models vary, depending on type:

• Origami : Göttingen flat-plate, or Jedelsky-form for folded leading edges.
• Compound Origami: Identical with origami, though often with sealed edges â€" 45% improvement in Cd.
• Profile Performance: Göttingen curved-plate, with profile similar to Göttingen 801.
• Scale Performance: Göttingen 801 or any other wing aerofoil
• Scale Models: This varies on model type (see below)

Camber of profiles varies, too. In general, the lower the Re, the greater the camber. Origami types will have 'ludicrous' or very high cambers in comparison with more marginally performing scale types, whose escalating masses demand higher flying speeds and so lower induced drag from high camber, though this will vary depending on type being modelled.

In the case of scale performance and scale models, the modellers intent will define the type of aerofoil section chosen. WWI biplanes, if designed for flight performance, will often have curved-plate aerofoils, as these produce a highly cambered surfaces and Coefficient of Lift (Cl) for low gliding airspeeds. WWII monoplanes will often have very scale-like sections, though with increased trailing edge droop to improve camber in comparison with scale counterparts.

Similarly, size, airspeed and mass will have very big impacts on choice of aerofoil, though this is a universal consideration in model plane design, no matter the material.

Origami Flying Wings

The former Guinness world record holder Tim Richardson disagrees with the decision to put a 'tail' on the paper plane. His explanation of paper plane aerodynamics on his website mentions that the tail is not needed. He uses the real-life B-2 Spirit flying wing bomber as an example, stating that the weights along the wing should be put forward in order to stabilize the plane. (Note: paper planes do not need a tail primarily because they typically have a large, thin fuselage, which acts to prevent yaw, and wings along the entire length, which prevents pitch.)

Independently, Edmond Hui invented a Stealth Bomber-like paper plane called the Paperang in 1977, based on hang glider aerodynamics. Uniquely, it has properly controlled airfoil sections, high-aspect-ratio wings, and a construction method designed to allow the builder to vary every aspect of its shape. It was the subject of a book, "Amazing Paper Airplanes" in 1987, and a number of newspaper articles in 1992. It is ineligible for most paper plane competitions due to the use of a staple, but it has extremely high gliding performance exceeding glide ratios of 12 to 1 with good stability.

In 1975, origami artist Michael LaFosse designed a pure origami (one sheet; no cutting, glue or staples...) flying wing, which he named the "Art Deco Wing".Though its aerodynamic form mimics some hang glider and supersonic airfoils, its invention evolved from exploring the beauty of folded paper first. Its glide ratio and stability are on a par with many of the best paper wing constructions that use glue, tape or staples. This design was first published in 1984 in the book "Wings and Things", by Stephen Weiss, St. Martin's Press.

Although it is a common view that light paper planes go farther than heavy ones, this is considered to be untrue by Blackburn. Blackburn's record-breaking 20-year-old paper plane was based on his belief that the best planes had short wings and are "heavy" at the point of the launch phase in which the thrower throws the paper plane into the air, and at the same time longer wings and a "lighter" weight would allow the paper plane to have better flight times but this cannot be thrown hard with much pressure into the air as a "heavy" weighted launch phase. According to Blackburn, "For maximum height and for a good transition to gliding flight, the throw must be within 10 degrees of vertical" â€" which shows that a speed of at least 60 miles per hour (97 kilometres per hour) is the amount needed to throw the paper plane successfully.

After the folding there are still gaps between different layers of folded paper (tearoff edge). These and the kinks transversal to the airflow may have a detrimental effect on aerodynamics, especially on the upper side of the wing. In some models the surfaces are not aligned to the direction of flow acting as airbrakes. Typically the center of mass is at 1/81 and the center of area is at 1/2 of the plane lengths. Two methods exist to shift the center of mass to the front. One rolls up the leading edge which then stays unswept. The other uses a swept wing or axial folding to produce something like a fuselage extending out of leading edge of the wing.

Other designs

It is possible to create freestyle versions of paper aircraft, which often exhibit an unusual flight path compared to more traditional paper darts, jets and gliders. Another propulsion technique, creating high launch velocities, involves the use of elastic bands for "catapults". Walkalong gliding involves the continuous propulsion of paper airplane designs (such as the tumblewing, follow foil and paper airplane surfer) by soaring flight on the edge of a sheet of cardboard.

Space flight

There may one day be a paper plane launched from space. A prototype passed a durability test in a wind tunnel in March 2008, and Japan's space agency JAXA considered a launch from the International Space Station. However, the plane developers, Takuo Toda (see World Records above) and fellow enthusiast Shinji Suzuki, an aeronautical engineer and professor at Tokyo University, postponed the attempt after acknowledging it would be all but impossible to track them during the planes' week-long journey to Earth, assuming any of them survived the searing descent. The developers were hoping that China or Russia will back further efforts on the project. In February 2011, 200 planes were launched from a net underneath a weather balloon twenty-three miles above Germany. The planes were designed to maintain stable flight even in gusts up to 100 mph. The planes were equipped with memory chips from which data can be uploaded. The planes were found in other places in Europe, North America and e ven Australia.

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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 goodsâ€"including clothing (e.g., shoes, hats, jackets, skirts, trousers, and belts), bookbinding, leather wallpaper, and as a furniture covering. It is produced in a wide variety of types and styles, decorated by a wide range of techniques.

Forms

Several tanning processes transform hides and skins into leather:

• Chrome-tanned leather, invented in 1858, is tanned using chromium sulfate and other chromium salts. 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 the ease and agility of this method make it a popular choice. 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 ingredients found in different vegetable matter, such as tree bark prepared in bark mills, wood, leaves, fruits, and roots. It is supple and brown in color, with the exact shade depending on the mix of chemicals and the color of the skin. 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 and becomes harder. In hot water, it shrinks drastically and partly congealsâ€"becoming rigid, and eventually 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. 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. This is the leather that most tanners refer to as wet-white leather due to its pale cream or white color. It is the main type of "chrome-free" leather, often seen in shoes for infants and automobiles.
• Formaldehyde tanning (being phased out due to danger to workers and sensitivity of many people to formaldehyde) is another aldehyde tanning method. Brain-tanned leathers fall into this category, and are exceptionally water absorbent.
• Brain tanned leathers are made by a labor-intensive process that uses emulsified oils, often those of animal brains such as deer, cattle, and buffaloes. They are known for their exceptional softness and washability.
• Chamois leather also falls into the category of aldehyde tanning, and like brain tanning, produces a porous and highly water-absorbent leather. Chamois leather is made using marine oils (traditionally cod oil) that oxidize easily to produce the aldehydes that tan the leather to color it.
• Rose-tanned leather is a variation of vegetable oil tanning and brain tanning, where pure rose otto replaces the vegetable oil and emulsified oils. Rose-tanned leather tanned leaves a powerful rose fragrance even years from when it is manufactured. 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.
• Synthetic-tanned leather is tanned using aromatic polymers such as the Novolac or Neradol types (syntans, contraction for synthetic tannins). This leather is white in color and was invented when vegetable tannins were in short supply during the Second World War. Melamine and other amino-functional resins fall into this category, as well, and they provide the filling that modern leathers often require. Urea-formaldehyde resins were also used in this tanning method before people realized the hazards that formaldehyde presents to tanners and consumers.
• Alum-tanned leather is transformed using aluminium salts mixed with a variety of binders and protein sources, such as flour and egg yolk. Alum-tanned leather is technically not tanned, as tannic acid is not used, and the resulting material reverts to rawhide if soaked in water long enough to remove the alum salts.
• Rawhide is made by scraping the skin thin, soaking it in lime, and then stretching it while it dries. Like alum-tanning, rawhide is not technically "leather", but is usually lumped in with the other forms. Rawhide is stiffer and more brittle than other forms of leather; it is primarily found in uses such as drum heads and parchment where it does not need to flex significantly; it is also cut up into cords for use in lacing or stitching and for making many varieties of dog chews.

Leather, usually vegetable-tanned, 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. Russia leather was an important international trade good for centuries. Frequent oiling of leather, with mink oil, neatsfoot oil, or a similar material keeps it supple and improves its lifespan dramatically.

Leather with the hair still attached is called "hair-on".

Types

In general, leather is sold in these four forms:

• Full-grain leather refers to hides that have not been sanded, buffed, or snuffed (as opposed to top-grain or corrected leather) to remove imperfections (or natural marks) on the surface of the hide. The grain remains allowing the fiber strength and durability. The grain also has breathability, resulting in less moisture from prolonged contact. Rather than wearing out, it develops a patina during its expected useful lifetime. High quality leather furniture and footwear are often made from full-grain leather. Full-grain leathers are typically available in two finish types: aniline, semi-aniline.
• Top-grain leather (the most common type in high-end leather products) is the second-highest quality. It has had the "split" layer separated away, making it thinner and more pliable than full-grain. Its surface has been sanded and a finish coat added, which produces a colder, plastic feel with less breathability, and it does not develop a natural patina. It is typically less expensive and has greater stain resistance than full-grain leather if the finish remains unbroken.
• Corrected-grain leather is any leather that has had an artificial grain applied to its surface. The hides used to create corrected leather do not meet the standards for use in creating vegetable-tanned or aniline leather. The imperfections are corrected or sanded off, and an artificial grain embossed into the surface and dressed with stain or dyes. Most corrected-grain leather is used to make pigmented leather as the solid pigment helps hide the corrections or imperfections. Corrected grain leathers can mainly be bought as two finish types: semi-aniline and pigmented.
• Split leather is leather created from the fibrous part of the hide left once the top-grain of the rawhide has been separated from the hide. During the splitting operation, the top-grain and drop split are separated. The drop split can be further split (thickness allowing) into a middle split and a flesh split. In very thick hides, the middle split can be separated into multiple layers until the thickness prevents further splitting. Split leather then has an artificial layer applied to the surface of the split and is embossed with a leather grain (bycast leather). Splits are also used to create suede. The strongest suedes are usually made from grain splits (that have the grain completely removed) or from the flesh split that has been shaved to the correct thickness. Suede is "fuzzy" on both sides. Manufacturers use a variety of techniques to make suede from full-grain. A reversed suede is a grained leather that has been designed into the leather article with the grain facin g away from the visible surface. It is not considered a true suede.

Less-common leathers include:

• Buckskin or brained leather is a tanning process that uses animal brains or other fatty materials to alter the leather. The resulting supple, suede-like hide is usually smoked heavily to prevent it from returning to a rawhide state, if wetted. It is easier to soften, and helps repel leather-eating bugs.
• Patent leather is leather that has been given a high-gloss finish. Inventor Seth Boyden developed the original process in Newark, New Jersey in 1818. Patent leather usually has a plastic coating.
• Fish leather is popular for its motifs and its pigmentation. Mainly used for making shoes and bags, the fish skin is tanned like other animal skins. The species used include salmon, perch, sturgeon, etc.
  • Salmon : farmed in Iceland and Norway, salmon skin has fine scales. Its strength and elegant look make it the most popular fish leather.
  • Perch : from the Nile, its skin is recognizable with large, round and soft scales
  • Wolffish : smooth, without scales, with dark spots, and stripes due to the friction of marine rocks
  • Cod : finer scales than salmon, but more varied texture, sometimes smooth and sometimes rough
  • Sturgeon : known for its eggs (caviar), its leather is quite expensive
  • Eel : without scales, its skin is shiny
  • Tilapia : originally from Africa and farmed in many places, tilapia leather is beautiful, with resistant qualities similar to salmon and perch
  • Shagreen is also known as stingray skin/leather. Applications used in furniture production date as far back as the art deco period. The word "shagreen" originates from France. It is known as the most difficult leather to work due to dished scales of the animal, and it is one of the most expensive leathers.
  • Shark is covered with small, close-set tubercles, making it very tough. Shark skin handbags were once in vogue, but interest has fallen as the material and production costs is very high. Moreover, this skin is more difficult to work. (Do not confuse with sharkskin, a woven textile product.
• Vachetta leather is used in the trimmings of luggage and handbags. The leather is left untreated and is therefore susceptible to water and stains. Sunlight makes the natural leather darken in shade (develop a patina).
• Slink is leather made from the skin of unborn calves. It is particularly soft and is valued for making gloves.
• Deerskin is a tough, water-resistant leather, possibly due to the animal's adaptations to its thorny and thicket-filled habitats. Deerskin has been used by many societies, including indigenous Americans. Most modern deerskin is no longer procured from the wild, with deer farms breeding the animals specifically for the purpose of their skins. Large quantities are still tanned from wild deer hides in historic tanning towns such as Gloversville and Johnstown in upstate New York. Deerskin is used in jackets and overcoats, martial arts equipment such as kendo bogu, as well as personal accessories such as handbags and wallets.
• Goatskin is soft but tough, and is used for items such as thorn-resistant gardener's gloves.
• Nubuck is top-grain cattle hide leather that has been sanded or buffed on the grain side, or outside, to give a slight nap of short protein fibers, producing a velvet-like surface.
• Russia leather is a particular form of bark-tanned cow leather. It is distinguished by an oiling step, after tanning, where birch oil is worked into the leather to make it particularly hard-wearing, flexible and resistant to water.

There are two other types of leather commonly used in specialty products, such as briefcases, wallets, and luggage:

• Belting leather is a full-grain leather originally used in driving pulley belts and other machinery. It is found on the surface of briefcases, portfolios, and wallets, and can be identified by its thick, firm feel and smooth finish. Belting leather is generally a heavy-weight of full-grain, vegetable-tanned leather.
• Napa leather is chrome-tanned and is soft and supple. It is commonly found in wallets, toiletry kits, and other personal leather goods.

The following are not "true" organic leathers, but are materials that contain leather fiber. Depending on jurisdiction, they may still be labeled as "Genuine Leather", even though the consumer generally can only see the outer layer of the material and can't actually see any of the leather content:

• Bonded leather or reconstituted leather is an economical material that uses leftover organic leather (from tanneries or workshops) that are shredded and bonded together with polyurethane or latex on to a fiber sheet. The varying degree of organic leather in the mix (10% to 90%) affects the smell and texture. Its reduced cost makes it popular for furniture upholstery, especially for commercial furniture that requires durabilityâ€"though durability can vary widely depending on the formulation.
• Bycast leather is a split leather with a layer of polyurethane laminated to the surface and then embossed. Bycast was originally made for the shoe industry, and later adopted by the furniture industry. The original formula created by Bayer was strong but expensive. The result is a material that is slightly stiffer but cheaper than top-grain leather but has a much more consistent texture. Because its surface is completely covered in plastic, is easier to clean and maintain, but is not easily repaired.

From other animals

Today, most leather is made of cattle skin, but many exceptions exist. Lamb and deerskin are used for soft leather in more expensive apparel. Deer and elkskin are widely used in work gloves and indoor shoes. Pigskin is used in apparel and on seats of saddles. Buffalo, goat, alligator, snake, ostrich, kangaroo, ox, and yak skins may also be used for leather.

Kangaroo leather is used to make items that must be strong but flexible. It is the material most commonly used in bullwhips. Some motorcyclists favor kangaroo leather for motorcycle leathers because of its light weight and abrasion resistance. Kangaroo leather is also used for falconry jesses, soccer footwear, and boxing speed bags. At different times in history, leather made from more exotic skins has been considered desirable. For this reason, certain species of snakes and crocodiles have been hunted.

Although originally raised for their feathers in the 19th century, ostriches are now more popular for both meat and leather. Different processes produce different finishes for many applications, i.e., upholstery, footwear, automotive products, accessories, and clothing. Ostrich leather is currently used by many major fashion houses such as Hermès, Prada, Gucci, and Louis Vuitton. Ostrich leather has a characteristic "goose bump" look because of the large follicles where the feathers grew.

In Thailand, stingray leather is used in wallets and belts. Sting ray leather is tough and durable. The leather is often dyed black and covered with tiny round bumps in the natural pattern of the back ridge of an animal. These bumps are then usually dyed white to highlight the decoration. Stingray rawhide is also used as grips on Chinese swords, Scottish basket hilted swords, and Japanese katanas. Stingray leather is also used for high abrasion areas in motorcycle racing leathers (especially in gloves, where its high abrasion resistance helps prevent wear through in the event of an accident.)

Production processes

The leather manufacturing process is divided into three fundamental subprocesses: preparatory stages, tanning, and crusting. All true leathers undergo these subprocesses. A further subprocess, surface coating, can be added into the leather process sequence, but not all leathers receive surface treatment. Since many types of leather exist, it is difficult to create a list of operations that all leathers must undergo.

The preparatory stages are when the hide/skin is prepared for tanning. Preparatory stages may include: preservation, soaking, liming, unhairing, fleshing, splitting, reliming, deliming, bating, degreasing, frizing, bleaching, pickling, and depickling.

Tanning is a process that stabilizes the protein of the raw hide or skin so it does not putrefy, 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 (or wetted-back) putrefy, while tanned material dries to a flexible form that does not become putrid when wetted-back.

Many tanning methods and materials exist. The choice ultimately depends on the end application for the leather. The most common tanning material is chromium, which leaves the tanned leather a pale blue color (due to the chromium). This product is commonly called wet blue. The hides, when finished pickling, are typically between pH 2.8 and 3.2. At this point, tannery workers load the hides into a drum and immerse them in a float that contains the tanning liquor. The hides soak while the drum slowly rotates about its axis, and the tanning liquor slowly penetrates through the full thickness of the hide. Workers periodically cut a cross-section of a hide and observe the degree of penetration. Once the process achieves even penetration, workers slowly raise the float's pH in a process called basification, which fixes the tanning material to the leatherâ€"and the more tanning material fixed, the higher the leather's hydrothermal stability and shrinkage temperature resistance. Chrome-tan ned leather pH is typically between pH 3.8 and 4.2.

Crusting is a process that thins, retans, and lubricates leather. It often includes a coloring operation. Chemicals added during crusting must be fixed in place. Crusting culminates with a drying and softening operation, and may include:

• Sammying
• Splitting
• Shaving
• Rechroming
• Neutralization
• Retanning
• Dyeing
• Fatliquoring
• Filling
• Stuffing
• Stripping
• Whitening
• Fixating
• Setting
• Drying
• Conditioning
• Milling
• Staking
• Buffing

For some leathers, workers apply a surface coating. Tanners call this finishing. Finishing operations can include:

• Oiling
• Brushing
• Padding
• Impregnation
• Buffing
• Spraying
• Roller coating
• Curtain coating
• Polishing
• Plating
• embossing
• Ironing, ironing-combing (for hair-on)
• Glazing
• tumbling

Environmental impact

Leather produces some environmental impact, most notably due to:

• The carbon footprint of cattle rearing
• Use of chemicals in the tanning process (e.g., chromium, formic acid, mercury and solvents)
• Air pollution due to the transformation process (hydrogen sulfide during dehairing and ammonia during deliming, solvent vapors)

Carbon footprint

One estimate of the carbon footprint of leather goods is 0.51 kg of CO₂ equivalent per £1 of output at 2010 retail prices, or 0.71 kg CO₂eq per £1 of output at 2010 industry prices.

Water footprint

One ton of hide or skin generally produces 20 to 80 m³ of waste water, including chromium levels of 100â€"400 mg/l, sulfide levels of 200â€"800 mg/l, high levels of fat and other solid wastes, and notable pathogen contamination. Producers often add pesticides to protect hides during transport. With solid wastes representing up to 70% of the wet weight of the original hides, the tanning process represents a considerable strain on water treatment installations.

Disposal

Leather biodegrades slowlyâ€"taking 25 to 40 years to decompose. However, vinyl and petrochemical-derived materials take 500 or more years to decompose.

Chemicals used in tanning

Tanning is especially polluting in countries where environmental regulations are lax, such as in India, the world's third-largest producer and exporter of leather. To give an example of an efficient pollution prevention system, chromium loads per produced tonne are generally abated from 8 kg to 1.5 kg. VOC emissions are typically reduced from 30 kg/t to 2 kg/t in a properly managed facility. A review of the total pollution load decrease achievable according to the United Nations Industrial Development Organization posts precise data on the abatement achievable through industrially proven low-waste advanced methods, while noting, "even though the chrome pollution load can be decreased by 94% on introducing advanced technologies, the minimum residual load 0.15 kg/t raw hide can still cause difficulties when using landfills and composting sludge from wastewater treatment on account of the regulations currently in force in some countries."

In Kanpur, the self-proclaimed "Leather City of World"â€"with 10,000 tanneries as of 2011 and a city of three million on the banks of the Gangesâ€"pollution levels were so high, that despite an industry crisis, the pollution control board decided to shut down 49 high-polluting tanneries out of 404 in July 2009. In 2003 for instance, the main tanneries' effluent disposal unit was dumping 22 tonnes of chromium-laden solid waste per day in the open. Scientists at the Central Leather Research Institute in India have developed biological methods for pretanning, as well as better chromium management.

In the Hazaribagh neighborhood of Dhaka in Bangladesh, chemicals from tanneries end up in Dhaka's main river. Besides the environmental damage, the health of both local factory workers and the end consumer is also negatively affected. Besides local sales of products made with leather from the Hazaribagh neighborhood of Dhaka, the leather is also bought by huge Western companies and sold in the developed world.

The higher cost associated with the treatment of effluents than to untreated effluent discharging leads to illegal dumping to save on costs. For instance, in Croatia in 2001, proper pollution abatement cost US$70â€"100 per ton of raw hides processed against $43/t for irresponsible behavior.

No general study seems to exist, but recent media reports are rife with examples. In November 2009, for example, one of Uganda's main leather companies was caught directly dumping waste water into a wetland adjacent to Lake Victoria.

Role of enzymes

Enzymes like proteases, lipases, and amylases have an important role in the soaking, dehairing, degreasing, and bating operations of leather manufacturing. Proteases are the most commonly used enzymes in leather production. The enzyme must not damage or dissolve collagen or keratin, but should hydrolyze casein, elastin, albumin, globulin-like proteins, and nonstructural proteins that are not essential for leather making. This process is called bating.

Lipases are used in the degreasing operation to hydrolyze fat particles embedded in the skin.

Amylases are used to soften skin, to bring out the grain, and to impart strength and flexibility to the skin. These enzymes are rarely used.

Preservation and conditioning

The natural fibers of leather break down with the passage of time. Acidic leathers are particularly vulnerable to red rot, which causes powdering of the surface and a change in consistency. Damage from red rot is aggravated by high temperatures and relative humidities. Although it is chemically irreversible, treatments can add handling strength and prevent disintegration of red rotted leather.

Exposure to long periods of low relative humidities (below 40%) can cause leather to become desiccated, irreversibly changing the fibrous structure of the leather. Chemical damage can also occur from exposure to environmental factors, including ultraviolet light, ozone, acid from sulfurous and nitrous pollutants in the air, or through a chemical action following any treatment with tallow or oil compounds. Both oxidation and chemical damage occur faster at higher temperatures.

Various treatments are available such as conditioners. Saddle soap is used for cleaning, conditioning, and softening leather. Leather shoes are widely conditioned with shoe polish.

Leather book binding

Leather used in book binding has many of the same preservation needs: protection from high temperatures, high relative humidity, low relative humidity, fluctuations in relative humidity, light exposure, dust buildup, pollution, mold, and insect infestation.

For books with red rot, acid-free phase boxes and/or polyester dust jackets (Dupont Mylar Type D or ICI Mellinex 516) are recommended to protect the leather from further handling damage and to prevent the residues from getting on hands, clothes, the text block, and nearby books.

The debate on the use of dressings for preservation of book bindings has spanned several decades as research and experimental evidence have slowly accumulated. The main argument is, when done incorrectly, multiple disadvantages exist, and when done correctly, little to no preservation advantage occurs. Pamphlets and guidelines give numerous downsides to dressings use, including: the dressing becoming increasingly acidic and discolors and stains the leather, oxidizes (penetration and expansion of oils including displacement and weakening of fibers) and stiffens, leave a sticky surface, collects dust, wicks into adjacent materials, forms unstable surface spews, encourages biological deterioration and mold growth, blocks surface porosity, impedes further treatment, wets and swells the leather, affects surface finishes, and desiccates the leather. Meanwhile, scientific experiments have shown no substantial benefits. The main authorities on the subject, therefore, discourage it, with a caveat for special cases done under the direction of a conservator. Leather can be decorated by a variety of methods, including pyrography and beading.

Cordwain and Cuir de Cordoue

Cordwain, once a synonym of cordovan (through Old French cordewan) meaning "from Córdoba" describes a certain kind of fine leather, originally from Córdoba. Cordwainer is still used to describe someone in the profession of shoemaking.

The related term Cuir de Cordoue refers to painted and gilded (and sometimes embossed) leather hangings manufactured in panels and assembled for covering walls as an alternative to tapestry.

In modern culture

Due to its excellent resistance to abrasion and wind, leather found a use in rugged occupations. The enduring image of a cowboy in leather chaps gave way to the leather-jacketed and leather-helmeted aviator. When motorcycles were invented, some riders took to wearing heavy leather jackets to protect from road rash and wind blast; some also wear chaps or full leather pants to protect the lower body. Many sports still use leather equipment. Its flexibility facilitates forming and shaping it into balls and protective gear.

Leather fetishism is the name popularly used to describe a fetishistic attraction to people wearing leather, or in certain cases, to the garments themselves.

Many rock groups (particularly heavy metal and punk groups in the 1980s) are well known for wearing leather clothing. Leather clothing, particularly jackets, are common in the heavy metal and Punk subculture. Extreme metal bands (especially black metal bands) and Goth rock groups have extensive leather clothing.

Many cars and trucks come with optional or standard "leather" seating.

Religious sensitivities

In religiously diverse countries, leather vendors typically clarify the kinds of leather in their products. For example, leather shoes bear a label that identifies the animal from which the leather came. This helps a Muslim not accidentally purchase pigskin, and a Hindu avoid cattle. Many vegetarian Hindus do not use any kind of leather. Such taboos increase the demand for religiously neutral leathers such as ostrich and deer.

Judaism forbids the comfort of wearing leather shoes on Yom Kippur, Tisha B'Av, and during mourning.

Jainism prohibits the use of leather, since it is obtained by killing animals.

Alternatives

Some vegetarians, vegans and animal rights activists and groups such as PETA, boycott and promote the boycotting of all leather products, arguing that the use of leather is unjustifiable. They encourage the use of alternative materials such as synthetic leathers.

Many synthetic leather materials have been developed. Some published claims assert that certain versions of artificial leather are stronger than real leather when manufactured with strength in mind. Ranges of synthetic polymeric materials provide features rivalling or exceeding those of various types of leather in particular applications; they include vegan microfiber, pleather and Naugahyde.

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