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159:, 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 (see image). Discs manufactured by PDO in other countries do not seem to be affected. A similar, if considerably less widespread problem occurred with discs manufactured by Optical Media Storage (Opti.Me.S) in Italy.
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There are also 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 reasons other than the manufacturing error that occurred at PDO. In particular, colour changes that occur along with the visible disintegration of the
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Affected discs show an uneven brownish discolouring that usually starts at the edge of the disc and slowly works its way toward the center. The top or label layer is affected before the bottom layer. The disc becomes progressively darker over time; tracks at the end of the disc (near the outer edge)
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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, and pledged to re-press new CDs until the year 2015 if a customer notices the corrosion problem. However, after a change of ownership, PDO (now
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However, storage conditions certainly seem to contribute to the speed of the decay, as some bronzed CDs were already reported as unreadable in the mid-1990s, whereas others were still playable as recently as 2012. As it was noted that CDs stored in paper sleeves were deteriorating sooner and faster
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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
187:. A combination of the two factors seems likely 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.
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EDC – Entertainment
Distribution Company) discontinued its helpline in 2006, and defective CDs are now no longer replaced by the manufacturer, even though some of the affected record labels continue to offer replacement compact discs.
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content of the paper in the booklets, which led to the corrosion of the aluminium layer of the disc, even though PDO later said it was because "a silver coating had been used on its discs instead of the standard gold."
142:, a type of corrosion that affects the reflective layer of compact discs and renders them unreadable over time. The phenomenon was first reported by John McKelvey in the September/October 1994 issue of
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PDO acknowledged that the problem was due to a manufacturing error on its part, but it gave different explanations for the problem. The most widely acknowledged explanation is that the
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At the time, PDO was contracted by several record companies, many of whose records may be affected. According to a list compiled on
Classical.net and other sources, these include
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As bronzing is a progressive effect that cannot be stopped, any PDO- or Opti.Me.S-manufactured CDs that are not yet showing any signs of bronzing by now are very likely safe.
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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.
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PDO also manufactured CDs that have an even yellowish-golden tint. This is due to a yellow dye in the disc and is unrelated to the bronzing effect.
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confirmed that silver instead of aluminium in the reflective layer of the CD would react with sulfur compounds in the sleeves, forming
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Bronzing is due to a fault in the manufacturing process and can therefore neither be prevented nor be stopped once it has begun.
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CD bronzing seems to occur mostly with audio CDs manufactured by
Philips and Dupont Optical (PDO) at its plant in
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sleeves are a notable safe exception. Similar measures are used for books suffering from acid deterioration.
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data layer (i.e. holes) are not typical of CD bronzing, but should be considered
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show an increasing number of disc-read errors before becoming unplayable.
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Classical.net article, with (now obsolete) PDO replacement information
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University of
Washington Libraries: Resources on CD rot and bronzing
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Association of Sound and Audiovisual Archives
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482:"PDO & CD Bronzing: Possibly Affected CDs by Label"
51:. Unsourced material may be challenged and removed.
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166:used to coat the discs was not resistant to the
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392:Music Library Association newsletter no. 122
322:sleeves are not considered safe because the
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111:Learn how and when to remove this message
565:EDC Blackburn (successor company of PDO)
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507:Lampson, L. David (September 1995).
49:adding citations to reliable sources
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603:Research shows vulnerability of CDs
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585:Article from American Record Guide
383:Hirsch, Barbara (September 2000).
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533:Howard, Richard (January 2007).
456:IASA Information Bulletin no. 22
422:"Is music safe on compact disc?"
337:, not the reflective layer, the
333:Because the recording is in the
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1015:Optical disc authoring software
36:needs additional citations for
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420:Bishop, Tom (27 August 2004).
16:Type of compact disc corrosion
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595:Hyperion Records support page
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177:British Library Sound Archive
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458:. July 1997. Archived from
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1005:CD copy protection schemes
580:BBC report on decaying CDs
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345:Customer support policy
127:CD affected by bronzing
60:"Compact disc bronzing"
205:Affected record labels
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1228:Materials degradation
368:American Record Guide
145:American Record Guide
132:Compact disc bronzing
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1024:Variants based on CD
989:Orange-Book-Standard
600:Fasoldt, Al (1990),
45:improve this article
452:"Bronzed CD alert!"
309:than CDs stored in
301:Preventing bronzing
259:Deutsche Grammophon
949:Portable CD player
829:CD copy protection
385:"Lasting Concerns"
239:Chapter 22 Records
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488:. 31 January 2006
401:on 24 August 2007
291:Testament Records
285:, Pearl Records,
223:Archiv Produktion
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183:, which has a
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173:Peter Copeland
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509:"CD Bronzing"
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62: –
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56:Find sources:
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40:
39:
34:This article
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28:
23:
22:
19:
1223:Compact disc
1087:Scarlet Book
853:
834:CD emulation
819:CD authoring
642:Compact disc
602:
544:. Retrieved
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528:
516:. Retrieved
512:
502:
490:. Retrieved
485:
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464:. Retrieved
460:the original
455:
429:. Retrieved
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403:. Retrieved
396:the original
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43:Please help
38:verification
35:
18:
1083:Hybrid SACD
1062:Purple Book
982:Court cases
956:CD recorder
854:CD bronzing
685:Yellow Book
675:Orange Book
311:jewel cases
287:RPO Records
271:IMP records
263:Globe Style
247:CRD Records
227:ASV Records
211:Ace Records
136:CD bronzing
1217:Categories
1202:Wiktionary
1103:Picture CD
901:Rock Ridge
871:CD-i Ready
861:CD subcode
844:CD ripping
824:CD burning
807:Technology
796:White Book
763:Beige Book
711:Green Book
354:References
71:newspapers
1144:LaserDisc
1113:VinylDisc
966:CD single
961:CD ripper
944:CD player
906:ISO 13490
881:El Torito
876:4ch CD-DA
774:shaped CD
740:(Karaoke)
727:Blue Book
315:acid-free
251:Danacords
157:Blackburn
1182:Category
1149:MiniDisc
1122:See also
1108:VideoNow
1068:DualDisc
1041:CD Video
1036:ATRAC CD
939:CD drive
886:ISO 9660
866:C2 error
759:Photo CD
665:Red Book
546:2 August
518:3 August
492:2 August
466:3 August
431:2 August
405:7 August
140:disc rot
101:May 2015
1192:Commons
1129:Blu-ray
1093:MovieCD
934:CD Case
749:Mini CD
744:Gold CD
718:CD-Text
221:, APR,
175:of the
164:lacquer
85:scholar
1139:HD DVD
1098:MP3 CD
891:Joliet
849:CD rot
696:CD-MRW
681:CD-ROM
193:CD rot
168:sulfur
87:
80:
73:
66:
58:
1058:DD-CD
998:Lists
896:Romeo
733:CD+EG
701:CD-MO
691:CD-RW
661:CD-DA
649:Discs
399:(PDF)
388:(PDF)
320:vinyl
255:Decca
134:, or
92:JSTOR
78:books
1164:WORM
1154:SACD
1073:HDCD
1053:cDVD
918:XRCD
786:SVCD
769:PMCD
738:CD+G
706:CD-i
671:CD-R
548:2007
520:2007
494:2007
468:2007
433:2007
407:2007
339:IASA
293:and
235:Cala
64:news
1159:UMD
1134:DVD
913:UDF
791:VCD
723:CD+
426:BBC
47:by
1219::
656:CD
537:.
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375:^
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108:(
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99:(
89:·
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41:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
