Compact Disc manufacturing
Compact disc manufacturing is the process by which commercial compact discs are replicated in mass quantities using a master version created from a source recording. This may be either in audio form or data form; this process is used in the mastering of read-only compact discs. A CD can be used to store audio and data in various standardized formats defined in the Rainbow Books. CDs are manufactured in a class 100 or better clean room. CD mastering differs from burning, as the pits and lands of a mastered CD are moulded into a CD blank, rather than being'burn marks' in a dye layer or areas with changed physical characteristics. In addition, CD burners write data sequentially, while a CD pressing plant'writes' the entire disk in one physical stamping operation. All CDs are pressed from a digital data source, with the most common sources being low error-rate CD-Rs or files from an attached computer hard drive containing the finished data; some CD pressing systems can use digital master tapes, either in Digital Audio Tape, Exabyte or Umatic formats.
However such sources are suitable only for production of audio CDs due to error detection and correction issues. If the source is not a CD, the table of contents for the CD to be pressed must be prepared and stored on the tape or hard drive. In all cases except CD-R sources, the tape must be uploaded to a media mastering system to create the TOC for the CD. Creative processing of the mixed audio recordings occurs in conventional CD premastering sessions; the term used for this is "mastering," but the official name, as explained in Bob Katz book, Mastering Audio, edition 1, page 18, is'premastering' because there still has to be the creation of another disc carrying the premastered audio which supplies the work surface on which the metal master will be electroformed. Glass mastering is performed in a class 100 or better clean room or a self-enclosed clean environment within the mastering system. Contaminants introduced during critical stages of manufacturing can cause sufficient errors to make a master unusable.
Once completed, a CD master will be less susceptible to the effects of these contaminants. During glass mastering, glass is used as a substrate to hold the CD master image while it is created and processed. Glass substrates, noticeably larger than a CD, are round plates of glass 240 mm in diameter and 6 mm thick, they also have a small, steel hub on one side to facilitate handling. The substrates are created specially for CD mastering and one side is polished until it is smooth. Microscopic scratches in the glass will affect the quality of CDs pressed from the master image; the extra area on the substrate allows for easier handling of the glass master and reduces risk of damage to the pit and land structure when the "father" stamper is removed from the glass substrate. Once the glass substrate is cleaned using detergents and ultrasonic baths, the glass is placed in a spin coater; the spin coater rinses the glass blank with a solvent and applies either photoresist or dye-polymer depending on the mastering process.
Rotation spreads dye-polymer coating evenly across the surface of the glass. The substrate is removed and baked to dry the coating and the glass substrate is ready for mastering. Once the glass is ready for mastering, it is placed in a laser beam recorder. Most LBRs are capable of mastering at greater than 1x speed, but due to the weight of the glass substrate and the requirements of a CD master they are mastered at no greater than 8x playback speed; the LBR uses a laser to write the information, with a wavelength and final lens NA chosen to produce the required pit size on the master blank. For example, DVD pits are smaller than CD pits, so a shorter wavelength or higher NA is needed for DVD mastering. LBRs use one of two recording techniques. Photoresist comes in two variations. Photoresist mastering uses a light-sensitive material to create the pits and lands on the CD master blank; the laser beam recorder uses a deep ultraviolet laser to write the master. When exposed to the laser light, the photoresist undergoes a chemical reaction which either hardens it or to the contrary makes it more soluble.
The exposed area is soaked in a developer solution which removes the exposed positive photoresist or the unexposed negative photoresist. Once the mastering is complete, the glass master is removed from the LBR and chemically'developed'. Once developing is finished, the glass master is metalized to provide a surface for the stamper to be formed onto, it is polished with lubrication and wiped down. When a laser is used to record on the dye-polymer used in non-photoresist mastering, the dye-polymer absorbs laser energy focused in a precise spot; this pit can be scanned by a red laser beam that follows the cutting beam, the quality of the recording can be directly and assessed. The pit geometry and quality of the playback can all be adjusted while the CD is being mastered, as the blue writing laser and the red r
Gold compact disc
A gold compact disc is one in which gold is used in place of the super pure aluminium used as the reflective coating on ordinary CDs or silver on ordinary CD-Rs Gold CDs can be played in any CD player. Blank gold CD-Rs are available, they can be played in any CD player. The advantage of the gold reflection layer is its increased resistance to corrosion, in contrast to the ordinary aluminium layer found on normal compact discs. Due to concerns over the incidence of CD rot on early CDs, gold CDs were thus seen as a potential solution. Many gold CDs, including those from Mobile Fidelity and DCC Compact Classics, are packaged in lift-lock cases, a special type of case where the CD is lifted out of the case automatically and a latch unlocked when opened; the advantage of this design is that only the edges of the disc are handled when removing it from the case, the disc is never subjected to any bending force while removing it. From the outside, they appear identical to a standard jewel case, they have the same dimensions as a standard jewel case, use standard booklets and back cards.
ABBA - Gold: Greatest Hits Al Stewart - Last Days of the Century Blondie - Parallel Lines Blood, Sweat & Tears - Child Is Father to the Man Bryan Adams - Reckless Counting Crows - August and Everything After David Bowie - The Man Who Sold the World David Bowie - The Rise and Fall of Ziggy Stardust and the Spiders from Mars David Bowie - Young Americans David Bowie - Station to Station David Bowie - Low David Bowie - "Heroes" David Bowie - Let's Dance David Bowie - Changesbowie Jimmy Buffett - Changes in Latitudes, Changes in Attitudes Jimmy Buffett - Son of a Son of a Sailor Jimmy Buffett - Songs You Know by Heart Bob Dylan - Highway 61 Revisited Bob Dylan - Blonde on Blonde The Doors - Strange Days The Eagles - Hell Freezes Over Joe Jackson - Night and Day Joe Jackson - Will Power Michael Jackson - Off the Wall Michael Jackson - Thriller Michael Jackson - Bad Michael Jackson - HIStory: Past and Future, Book I Michael Jackson - Michael Jackson's Ghosts - Limited Edition Minimax CD Elton John - Elton John's Greatest Hits Enya - The Memory of Trees Jefferson Airplane - Surrealistic Pillow Jethro Tull - Aqualung Jean-Michel Jarre - Équinoxe Jean-Michel Jarre - Oxygène John Coltrane - Blue Train John Coltrane and Paul Quinichette - Cattin' with Coltrane and Quinichette John Lennon - Imagine Metallica - Master of Puppets Nirvana - Nevermind Nirvana - In Utero Pat Benatar - In the Heat of the Night Paul & Linda McCartney - Ram Pink Floyd - Atom Heart Mother Pink Floyd - The Dark Side of the Moon Pink Floyd - Meddle Pink Floyd - Wish You Were Here Pink Floyd - The Wall Sonny Rollins - Sonny Rollins and the Contemporary Leaders The Police - Ghost in the Machine R.
E. M. - Murmur Red Hot Chili Peppers - Mother's Milk The Who - Who's Next Yuridia - Entre Mariposas Compact disc Enhanced CD Remastering CD rot Gold album Audiophile Mobile Fidelity Sound Lab Super Audio CD Extended Resolution Compact Disc
MiniDisc is a magneto-optical disc-based data storage format offering a capacity of 60, 74 minutes and 80 minutes, of digitized audio or 1 gigabyte of Hi-MD data. Sony brand audio players were on the market in September 1992. Sony announced the MiniDisc in September 1992 and released it in November of that year for sale in Japan and in December in Europe, the USA and other countries; the music format was based on ATRAC audio data compression, but the option of linear PCM digital recording was introduced to meet audio quality comparable to that of a compact disc. MiniDiscs were popular in Japan and found moderate success in Europe. Sony has ceased development of MD devices, with the last of the players sold by March 2013. In 1983, just a year after the introduction of the Compact Disc, Kees Schouhamer Immink and Joseph Braat presented the first experiments with erasable magneto-optical Compact Discs during the 73rd AES Convention in Eindhoven, it took, however 10 years before their idea was commercialized.
Sony's MiniDisc was one of two rival digital systems, both introduced in 1992, that were targeted as replacements for the Philips Compact Cassette analog audio tape system: the other was Digital Compact Cassette, created by Philips and Matsushita. Sony had intended Digital Audio Tape to be the dominant home digital audio recording format, replacing the analog cassette. Due to technical delays, DAT was not launched until 1989, by the U. S. dollar had fallen so far against the yen that the introductory DAT machine Sony had intended to market for about $400 in the late 1980s now had to retail for $800 or $1000 to break putting it out of reach of most users. Relegating DAT to professional use, Sony set to work to come up with a simpler, more economical digital home format. By the time Sony came up with MiniDisc in late 1992, Philips had introduced a competing system, DCC; this created marketing confusion similar to the Betamax versus VHS battle of the late 1970s and early 1980s. Sony attempted to license MD technology to other manufacturers, with JVC, Pioneer and others all producing their own MD systems.
However, non-Sony machines were not available in North America, companies such as Technics and Radio Shack tended to promote DCC instead. Despite having a loyal customer base of musicians and audio enthusiasts, MiniDisc met with only limited success in the United States, it was popular in Japan during the 1990s, but did not enjoy comparable sales in other world markets. Since recordable CDs, flash memory and HDD and solid-state-based digital audio players such as iPods have become popular as playback devices; the initial low uptake of MiniDisc was attributed to the small number of pre-recorded albums available on MD as few record labels embraced the format. The initial high cost of equipment and blank media was a factor. Mains-powered hi-fi MiniDisc player/recorders never got into the lower price ranges, most consumers had to connect a portable machine to the hi-fi in order to record; this inconvenience contrasted with the earlier common use of cassette decks as a standard part of an ordinary hi-fi set-up.
MiniDisc technology was faced with new competition from the recordable compact disc when it became more affordable to consumers beginning around 1996. Sony believed that it would take around a decade for CD-R prices to become affordable - the cost of a typical blank CD-R disc was around $12 in 1994 - but CD-R prices fell much more than envisioned, to the point where CD-R blanks sank below $1 per disc by the late 1990s, compared to at least $2 for the cheapest 80-minute MiniDisc blanks; the biggest competition for MiniDisc came from the emergence of MP3 players. With the Diamond Rio player in 1998 and the Apple iPod, the mass market began to eschew physical media in favor of file-based systems. By 2007, because of the waning popularity of the format and the increasing popularity of solid-state MP3 players, Sony was producing only one model, the Hi-MD MZ-RH1 available as the MZ-M200 in North America packaged with a Sony microphone and limited Apple Macintosh software support; the introduction of the MZ-RH1 allowed users to move uncompressed digital recordings back and forth from the MiniDisc to a computer without the copyright protection limitations imposed upon the NetMD series.
This allowed the MiniDisc to better compete with MP3 players. However, most pro users like broadcasters and news reporters had abandoned MiniDisc in favor of solid-state recorders, due to their long recording times, open digital content sharing, high-quality digital recording capabilities and reliable, lightweight design. On 7 July 2011, Sony announced that it would no longer ship MiniDisc Walkman products as of September 2011 killing the format. On 1 February 2013, Sony issued a press release on the Nikkei stock exchange that it will cease shipment of all MD devices, with last of the players to be sold in March 2013. However, it would continue to offer repair services. MD Data, a version for storing computer data, was announced by Sony in 1993 but never gained significant ground, its media were incompatible with standard audio MiniDiscs, cited as one of the main reasons behind the format's failure. MD Data could not write to audio-MDs, only the more expensive data blanks. In 1997, MD-Data2 blanks were introduced.
They were only implemented in Sony's short-lived MD-based camcorder as well as a small number of multi-track recorders.
Photo CD is a system designed by Kodak for digitizing and saving photos onto a CD. Launched in 1992, the discs were designed to hold nearly 100 high quality images, scanned prints and slides using special proprietary encoding. Photo CDs are defined in the Beige Book and conform to the CD-ROM XA and CD-i Bridge specifications as well, they were intended to play on CD-i players, Photo CD players, any computer with a suitable software. The system failed to gain mass usage among consumers due to its proprietary nature, the decreasing scanner prices, the lack of CD-ROM drives in most home personal computers of the day. Furthermore, Photo CD relied on CRT-based TV sets for home use. However, these were designed for moving pictures, their typical flicker became an issue. The Photo CD system gained a fair level of acceptance among professional photographers due to the low cost of the high quality film scans. Prior to Photo CD, professionals who wished to digitize their film images were forced to pay much higher fees to obtain drum scans of their film negatives and transparencies.
The Kodak Pro Photo CD Master Disc contains 25 images with maximum resolution of 6144 x 4096 pixels. This type is appropriate for 120 film, 4x5, but for small picture film, if highest resolution is required. Separate from the Photo CD format is Kodak's proprietary "Portfolio CD" format, which combines Red Book CD audio and Beige Book PCD with interactive menus and hotspots on PCD images; some standalone Philips Photo/Audio CD players could play Portfolio CDs, Windows player application was available. The Kodak Portfolio CD is not defined in any particular Rainbow Book; the Photo CD system was announced by Kodak in 1990. Photo CD targeted a full range of photographic needs, ranging from consumer level point-and-shoot cameras to high-end professionals using large format 4x5 sheet film; the first Photo CD products, including scanners for processing labs and Photo CD players for consumers, became available in 1992. The project was expected to be a $600 million business by 1997 with $100 million in operational earnings.
Kodak entered into a number of partnerships grow the usage of Photo CD. This included, for example, an arrangement with L. L. Bean in 1992 by which the catalog would be distributed in Photo CD format, an arrangement with Silicon Graphics in 1993 to make all Silicon Graphics image-processing workstations capable of accepting Kodak Photo CD optical disks; these measures, together with the relatively low cost of $3 per image and convenience, made Photo CD the digital imaging solution of choice for many photographers in the mid to late 1990s. By 2000, over 140 Photo CD processing labs in the U. S. were active, with many more outside the U. S. However, by the late 1990s, Photo CD was being eclipsed by alternate formats based on the industry standard JPEG format. In the consumer segment, the Photo CD format's inefficient compression scheme meant that Photo CD files were larger than a JPEG files of similar quality, thus less convenient for transmission across the internet, etc. For example, a 16Base Photo CD image of 5.5 Mb can be encoded as a JPEG image of 2.1 Mb at 80% quality, visually indistinguishable from the original.
When the Photo CD format was designed in the early 1990s, a design goal was to allow low cost playback-to-TV devices. At that time the available technology precluded 2-dimensional compression schemes such as JPEG, but by the late 1990s, advances in microprocessor technology had moved JPEG/PNG compression to well within the range of very low cost consumer electronics. In the professional and advanced amateur segments, Photo CD had been eclipsed by low cost desktop scanners such as those from Nikon and Minolta in the mid range, by drum scanners at the high end. While the pixel resolution of Photo CD was still comparable or better than the alternatives, Photo CD suffered from a number of other disadvantages. Firstly, the Photo CD color space, designed for TV display, is smaller than what can be achieved by a low cost desktop scanner. Secondly, the color rendition of Photo CD images changed over time and with different scanner versions. Thirdly, the dynamic range of scans was lower than for desktop scanners.
Tests at the time indicated that the dmax rating of Photo CD was 2.8-3.0, while available desktop scanners were reaching 4.2, a substantial difference. As a result of this, Photo CD's problems with color rendering, by 2004 the professional segment of the user community had turned against Photo CD. In the retail segment, while Photo CD was relatively popular with consumers, it was an economic failure for processing labs. At the time of its introduction, Kodak claimed that processing costs to labs would be close to $1 per image, which would allow the lab profitably sell at the $3 per image mark; however this promise was never realized resulting in the scanning process being rushed, with a resulting fall in quality. As a result of Photo CD's loss of market share and substantial corporate losses attributed by Kodak Management to its scanning business, Kodak abandoned the format over the period 2001-2004. By 2004, Kodak 4050 Photo CD scanners were being offered for free to anyone that would pay for their removal by more than one processing lab.
This abandonment generated considerable controversy both at the time and subsequently as the Photo CD format's technical specifications have never been released by Kodak. Photo CD remains an quoted example of an “orphan format” and o
A CD single is a music single in the form of a compact disc. The standard in the Red Book for the term CD single is an 8cm CD, it now refers to any single recorded onto a CD of any size the CD5, or 5-inch CD single. The format was introduced in the mid-1980s but did not gain its place in the market until the early 1990s. With the rise in digital downloads in the early 2010s, sales of CD singles have decreased. Commercially released CD singles can vary in length from two songs up to six songs like an EP; some contain multiple mixes of one or more songs, in the tradition of 12" vinyl singles, in some cases, they may contain a music video for the single itself as well as a collectible poster. Depending on the nation, there may be limits on the number of songs and total length for sales to count in singles charts. Dire Straits' "Brothers in Arms" is reported to have been the world's first CD single, issued in the UK in two separate singles as a promotional item, one distinguished with a logo for the tour, Live in'85, a second to commemorate the Australian leg of the tour marked Live in'86.
Containing four tracks, it had a limited print run. The first commercially released CD Single was Angeline by John Martyn released on 1 February 1986. CD singles were first made eligible for the UK Singles Chart in 1987, the first number 1 available on the format in that country was "I Wanna Dance with Somebody" by Whitney Houston in May 1987; the Mini CD single CD3 format was created for use for singles in the late 1980s, but met with limited success in the US. The smaller CDs were more successful in Japan and had a resurgence in Europe early this century, marketed as "Pock it" CDs, being small enough to fit in a shirt pocket. By 1989, the CD3 was in decline in the US, it was common in the 1990s for US record companies to release both a two-track CD and a multi-track maxi CD. In the UK, record companies would release two CDs but these consisted of three tracks or more each. During the 1990s, CD single releases became less common in certain countries and were released in smaller editions, as the major record labels feared they were cannibalizing the sales of higher-profit-margin CD albums.
Pressure from record labels made singles charts in some countries become song charts, allowing album cuts to chart based only on airplay, without a single being released. In the US, the Billboard Hot 100 made this change in December 1998, after which few songs were released in the CD single format in the US, but they remained popular in the UK and other countries, where charts were still based on single sales and not radio airplay. At the end of the 1990s, the CD was the biggest-selling single format in the UK, but in the US, the dominant single format was airplay. With the advent of digital music sales, the CD single has been replaced as a distribution format in most countries, most charts now include digital download counts as well as physical single sales. In Australia, the Herald Sun reported the CD single is "set to become extinct". In early July 2009, leading music store JB Hi-Fi ceased stocking CD singles because of declining sales, with copies of the week's No. 1 single selling as few as only 350 copies across all their stores nationwide.
While CD singles no longer maintain their own section of the store, copies are still distributed but placed with the artist's albums. That is predominantly the case for popular Australian artists such as Jessica Mauboy, Kylie Minogue and, most Delta Goodrem, whose then-recent singles were released on CD in limited quantities; the ARIA Singles Chart is now "predominantly compiled from legal downloads", ARIA stopped compiling their physical singles sales chart. "On a Mission" by Gabriella Cilmi was the last CD single to be stocked in Kmart and Big W, who concluded stocking newly released singles. Sanity Entertainment, having resisted the decline for longer than the other major outlets, has ceased selling CD singles. In China and South Korea, CD single releases have been rare since the format was introduced, due of the amount of infringement and illegal file sharing over the internet, most of the time singles have been album cuts chart based only on airplay, but with the advent of digital music the charts have occasionally included digital download counts.
In Greece and Cyprus, the term "CD single" is used to describe an extended play in which there may be anywhere from three to six different tracks. These releases charted on the Greek Singles Chart with songs released as singles; the original CD single is a music single released on a mini Compact Disc that measures 8 cm in diameter, rather than the standard 12 cm. They are manufactured using the same methods as standard full-size CDs, can be played in most standard audio CD players and CD-ROM disc drives; the format was first released in the United States, United Kingdom, France, West Germany, Hong Kong in 1987 as the replacement for the 7-inch single. While mini CDs have fallen out of popularity among most major record labels, they remain a popular, low cost way for independent musicians and groups to release music. Capable of holding up to 20 minutes of music, most mini CD singles contain at least two tracks, ofte
The PlayStation 3 is a home video game console developed by Sony Computer Entertainment. It is the successor to PlayStation 2, is part of the PlayStation brand of consoles, it was first released on November 11, 2006, in Japan, November 17, 2006, in North America, March 23, 2007, in Europe and Australia. The PlayStation 3 competed against consoles such as Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles; the console was first announced at E3 2005, was released at the end of 2006. It was the first console to use Blu-ray Disc as its primary storage medium; the console was the first PlayStation to integrate social gaming services, including the PlayStation Network, as well as the first to be controllable from a handheld console, through its remote connectivity with PlayStation Portable and PlayStation Vita. In September 2009, the Slim model of the PlayStation 3 was released, it no longer provided the hardware ability to run PS2 games. It was lighter and thinner than the original version, featured a redesigned logo and marketing design, as well as a minor start-up change in software.
A Super Slim variation was released in late 2012, further refining and redesigning the console. During its early years, the system had a critically negative reception, due to its high price, a complex processor architecture and a lack of quality games, but was praised for its Blu-ray capabilities and "untapped potential"; the reception would get more positive over time. The system had a slow start in the market but managed to recover after the introduction of the Slim model, its successor, the PlayStation 4, was released in November 2013. On September 29, 2015, Sony confirmed that sales of the PlayStation 3 were to be discontinued in New Zealand, but the system remained in production in other markets. Shipments of new units to Europe and Australia ended in March 2016, followed by North America which ended in October 2016. Heading into 2017, Japan was the last territory where new units were still being produced until May 29, 2017, when Sony confirmed the PlayStation 3 was discontinued in Japan.
The PlayStation 3 began development in 2001 when Ken Kutaragi the President of Sony Computer Entertainment, announced that Sony, IBM would collaborate on developing the Cell microprocessor. At the time, Shuhei Yoshida led a group of programmers within this hardware team to explore next-generation game creation. By early 2005, focus within Sony shifted towards developing PS3 launch titles. Sony unveiled PlayStation 3 to the public on May 16, 2005, at E3 2005, along with a boomerang-shaped prototype design of the Sixaxis controller. A functional version of the system was not present there, nor at the Tokyo Game Show in September 2005, although demonstrations were held at both events on software development kits and comparable personal computer hardware. Video footage based on the predicted PlayStation 3 specifications was shown; the initial prototype shown in May 2005 featured two HDMI ports, three Ethernet ports and six USB ports. Two hardware configurations were announced for the console: a 20 GB model and a 60 GB model, priced at US$499 and US$599, respectively.
The 60 GB model was to be the only configuration to feature an HDMI port, Wi-Fi internet, flash card readers and a chrome trim with the logo in silver. Both models were announced for a simultaneous worldwide release: November 11, 2006, for Japan and November 17, 2006, for North America and Europe. On September 6, 2006, Sony announced that PAL region PlayStation 3 launch would be delayed until March 2007, because of a shortage of materials used in the Blu-ray drive. At the Tokyo Game Show on September 22, 2006, Sony announced that it would include an HDMI port on the 20 GB system, but a chrome trim, flash card readers, silver logo and Wi-Fi would not be included; the launch price of the Japanese 20 GB model was reduced by over 20%, the 60 GB model was announced for an open pricing scheme in Japan. During the event, Sony showed 27 playable PS3 games running on final hardware. PlayStation 3 was first released in Japan on November 11, 2006, at 07:00. According to Media Create, 81,639 PS3 systems were sold within 24 hours of its introduction in Japan.
Soon after its release in Japan, PS3 was released in North America on November 17, 2006. Reports of violence surrounded the release of PS3. A customer was shot, campers were robbed at gunpoint, customers were shot in a drive-by shooting with BB guns, 60 campers fought over 10 systems; the console was planned for a global release through November, but at the start of September the release in Europe and the rest of the world was delayed until March. With it being a somewhat last-minute delay, some companies had taken deposits for pre-orders, at which Sony informed customers that they were eligible for full refunds or could continue the pre-order. On January 24, 2007, Sony announced that PlayStation 3 would go on sale on March 23, 2007, in Europe, the Middle East and New Zealand; the system sold about 600,000 units in its first two days. On March 7, 2007, the 60 GB PlayStation 3 launched in Singapore with a price of S$799; the console was launched in South Korea on June 16, 2007, as a single version equipped with an 80 GB hard drive and IPTV.
Following speculation that Sony was working on a'slim' model, Sony announced the PS3 CECH-2000 model on August 18, 2009, at the Sony Gamescom press conference
Compact disc bronzing
Compact disc bronzing, or CD bronzing, is a specific variant of disc rot, a type of corrosion that affects the reflective layer of CDs and renders them unreadable over time. The phenomenon was first reported by John McKelvey in the September/October 1994 issue of American Record Guide. Affected discs show an uneven brownish discoloring that starts at the edge of the disc and works its way toward the center; the top or label layer is affected before the bottom layer. The disc becomes progressively darker over time. CD bronzing seems to occur with audio CDs manufactured by Philips and Dupont Optical at its plant in Blackburn, Lancashire, UK, between the years 1988 and 1993. Most, but not all, of these discs have "Made in U. K. by PDO" etched into them. Discs manufactured by PDO in other countries do not seem to be affected. A similar, if less widespread problem occurred with discs manufactured by Optical Media Storage in Italy.. PDO acknowledged that the problem was due to a manufacturing error on its part, but it gave different explanations for the problem.
The most acknowledged explanation is that the lacquer used to coat the discs was not resistant to the sulfur content of the paper in the booklets, which led to the corrosion of the aluminium layer of the disc though PDO said it was because "a silver coating had been used on its discs instead of the standard gold." Peter Copeland of the British Library Sound Archive confirmed that silver instead of aluminium in the reflective layer of the CD would react with sulfur compounds in the sleeves, forming silver sulfate, which has a bronze colour. A combination of the two factors seems because, as Barbara Hirsch of the University of California points out, the oxidation could only have occurred if the protective lacquer did not seal the metal film and substrate well enough. There are isolated reports of CD discolouring with discs from other pressing plants, but these do not seem to be as widespread and may be due to other reasons than the manufacturing error that occurred at PDO. In particular, colour changes that occur along with the visible disintegration of the data layer are not typical of CD bronzing, but should be considered CD rot.
PDO manufactured CDs that have an yellowish-golden tint. This is unrelated to the bronzing effect; as bronzing is a progressive effect that cannot be stopped, any PDO-manufactured CDs that are not yet showing any signs of bronzing by now are likely safe. At the time, PDO was contracted by several record companies. According to a list compiled on Classical.net and other sources, these include Chapter 22 Records, Ace Records, Albany Records, Appian Records, APR, Archiv Produktion, ASV Records, Baseline Records, Collins Classics, CRD Records, Decca, Deutsche Grammophon, Globe Style, Hyperion Records, IMP records, L'Oiseau-Lyre, London Records, Memoir Records, Pearl Records, RPO Records, Testament Records and Unicorn-Kanchana. Bronzing is due to a fault in the manufacturing process and can therefore neither be prevented nor be stopped once it has begun. However, storage conditions seem to contribute to the speed of the decay, as some bronzed CDs were reported as unreadable in the mid-1990s, whereas others were still playable as as 2012.
As it was noted that CDs stored in paper sleeves were deteriorating sooner and faster than CDs stored in jewel cases, it is that storing CDs in an acid-free environment might slow down the bronzing effect. A minimum measure would be to remove the booklet and paper inlay from the CD's jewel case, though it might be advisable to store affected CDs in envelopes made of alkaline paper inside a box made of acid-free cardboard. Plastic or vinyl sleeves are not considered safe because the softening agents in the plastic may lead to further corrosion. Similar measures are used for books suffering from acid deterioration; because the recording is in the polycarbonate, not the reflective layer, the IASA has pointed out that in principle it would be possible to split the sandwich and re-coat the polycarbonate with aluminium to conserve the data on the disc. When the problem became known in the early 1990s, PDO offered to replace any discs thus affected if supplied with the defective disc and proof of purchase, pledged to re-press new CDs until the year 2015 if a customer notices the corrosion problem.
However, after a change of ownership, PDO discontinued its helpline in 2006, defective CDs are now no longer replaced by the manufacturer though some of the affected record labels continue to offer replacement compact discs. EDC Blackburn IASA – International Association of Sound and Audiovisual Archives University of Washington Libraries: Resources on CD rot and bronzing BBC report on decaying CDs Article from American Record Guide Classical.net article, with PDO replacement information Hyperion Records support page Fasoldt, Al, Research shows vulnerability of CDs, The Syracuse Newspapers