Back in 1981, when Kieran Prendiville was scratching these fancy new, silvery discs on the BBC’s Tomorrow’s World programme, they were presented as being virtually indestructible. No one could have had an idea that some of these futuristic sound carriers would end up the colour of autumn leaves – and also sounding like the rustle of autumn leaves underfoot – and worse. What is PDO CD bronzing, and how can you tell if your CDs are affected?
What is CD bronzing?
CD bronzing is a specific type of disc rot, commonly associated with CDs manufactured in the UK by a company called PDO between 1988 and 1993. That’s not to say that CDs manufactured by other companies, in other countries, and at other times, aren’t susceptible to disc rot, and even CD bronzing. But the problem is most associated with CDs made in the UK by this company in that period. An enormous amount of CDs produced in the UK at that time were made by PDO, as the company was the in-house manufacturer for one of the major record companies, as well as manufacturing CDs for lots of independent labels.
The commonly held reason given at the time states that the lacquer used to coat the discs was not resistant to the sulphur content of the paper booklets or packaging, leading to the CDs’ aluminium coating corroding. The lacquer is the clear, plastic coating that protects the music on the aluminium layer below. Aluminium is subject to oxidisation when it comes into contact with air. Once oxidised, it is unable to reflect the laser beam that is used to read the digital data it stores. Therefore, if air gets through to the aluminium through the faulty lacquer, the disc gradually becomes unplayable. The disc surface is ‘eaten’.
The process starts at the outer edge and works towards the centre. The label side is affected first, and it then spreads to the playing side. Because CDs are read from the centre to the edge, the last track(s) are first to become affected. Read errors and crackles appear, and these multiply until the affected disc gradually becomes unplayable.
Sometimes, bronzed CDs which look as if they ought to be unplayable can sometimes still play (more or less) OK – if so, rip them to your computer as quick as you can! But other times, potentially affected CDs which at first glance seem to have got off lightly can be completely unplayable.
Discs manufactured by PDO also included a subtle yellow dye, purely for cosmetic reasons. They therefore looked less ‘silvery’ than some other discs. This was totally normal, and is not a case of CD bronzing. The company also manufactured CDs that were deliberately a golden colour. And as if that wasn’t enough, they also manufactured 5″ CDVs, and CDVs were always gold, irrespective of who manufactured them. I hope that’s clear!
Which CDs are susceptible to PDO disc bronzing?
Potentially affected by the PDO CD bronzing problem are all CDs made by PDO in the UK from 1988 to 1993. CDs made by PDO in Germany (or West Germany, as it still was for part of this period) are unaffected. (Which is not to say that all other CDs manufactured by any company, at any time, will always play perfectly for ever, as that’s clearly not the case!).
PDO (Philips and Dupont Optical) was the in-house manufacturer for the PolyGram major record company. (Back in those days, the market hadn’t consolidated as much as it has now. The company has long since been part of Universal Music.)
This means that all CDs released on PolyGram company labels in this period could potentially be affected. The PolyGram family spanned the Polydor, Phonogram (Mercury, Fontana), London, A&M, Island, Deutsche Grammophon and Decca labels, among others. That’s a lot of music!
“Aha!” you exclaim, “Major labels are the spawn of Satan: I only ever bought independently released music in genres X and Y!” Yes, I was (and am!) like that too. Releases on major labels were welcomed into my home with all the hesitancy and trepidation I’d afford a disorientated dog with diarrhoea. But the problem is, PDO UK also manufactured CDs for a whole host of external labels, and was a popular choice for independent labels large and small.
PDO UK customers therefore included larger, well-known independent labels, such as Factory and Warp (and for classical music, Hyperion and ASV), plus smaller labels who, by accident or design, found themselves having some mainstream success, even if only for a few releases, for a short time. Remember this was the era of the second summer of love, Madchester and the explosion of all kinds of dance music. Indie bands who had been plugging away for years changed their sound and suddenly found themselves in the limelight, and new technology made it easier for people to produce dance tracks in their bedrooms, which many did.
On top of this, labels which generally had their CDs made at different plants also sometimes used PDO for certain titles. Presumably for capacity reasons, but also to manufacture CDs with full-colour printed labels, which were still something of a novelty, especially at the start of this period. The label sides often just featured the record company logo and the artist, title and track information in a standard typeface and colour scheme. Boring!
All in all, a problem for anyone in the UK who was actively interested in music and buying CDs in the late 1980s and early 1990s. Music lovers outside the UK will be less affected, as many titles were released on other labels in mainland Europe, North America, Japan and Australasia, and were therefore pressed by other companies.
How to tell if your CDs are affected
If you’re too young to have been buying CDs between 1988 and 1993, then you’re in luck. Unless you have since bought any potentially affected CDs from this period second hand.
Simply check the text around the hub (centre hole), on the playing side. All discs potentially affected by the PDO disc rot/bronzing problem will say MADE IN UK BY PDO around the hole.
If your disc does say MADE IN UK BY PDO, then it’s a candidate to look at more closely.
Discs manufactured by PDO after they rectified the problem in year 1993 are unaffected by disc rot. How can you find out if your disc was made before the problem was fixed, or after?
- When was the CD released? If the copyright text states 1994 or after, then you’re safe, as the problem had been fixed by then
- If your CD was released within the period 1988 to 1993, that doesn’t mean to say that your copy wasn’t manufactured later. If you know for a fact that you got a new copy of it for your 18th birthday in 1995, then you’re also safe.
- Find your potentially affected CDs on Discogs. Listings for CDs that could potentially be affected sometimes have a note to that effect.
- Hold your CD by the edges (which is how you should be holding them anyway – see my article on handling, storing and cleaning CDs). The CDs made by PDO in the ‘disc bronzing’ era have very ‘rounded’ edges. The CDs they made after solving the CD bronzing problem had ‘sharper’, less rounded edges. (Note that CDs made by PDO in Germany at this time also had ‘rounded’ edges, but the text helps you here: if it says MADE IN GERMANY (or W. GERMANY) by PDO, you’re safe!
If this text doesn’t appear around the centre hole, in other words, if it says it was made by some other company, your disc will be unaffected by PDO disc bronzing. (Which isn’t to say that it won’t be susceptible to other kinds of disc rot now or in future!)
PDO’s disc replacement scheme (RIP)
Back in the 1990s, when the CD bronzing problem first became apparent, PDO pledged to offer replacements up to the year 2015, presumably on the basis that any CDs which hadn’t displayed problems after 20+ years would be OK for the longer term. Music lovers with affected CDs could follow the instructions on the company’s website and receive new, problem-free pressings of their faulty CDs.
I took advantage of this service, receiving 50 or so replacements. But the company later changed ownership, became EDC, and put a stop to the replacement service in 2006. Well, thanks a lot! Since then, dozens more of my PDO CDs from this period have deteriorated or are now totally useless.
Can bronzed CDs be cured or repaired?
If your CD has developed crackles or has been rendered unplayable, there’s nothing you can do to repair that particular CD. If it’s discoloured, but plays OK, get it ripped to your computer right this second! If you rip CDs that crackle, the crackles are transferred too.
Help! Where can I find the music from all my bronzed CDs?
In an ideal world, we’d be able to go back in time in a time machine, so we could take advantage of PDO’s replacement scheme. Otherwise, the options are to find the music again, where possible (grrr!). This can be easier said than done, and can also potentially be expensive.
Later pressings of the same CD
A lot of affected titles were later repressed on CD by the original label after the problem had been solved. This applies to titles that were successful enough to warrant repressing. In most cases, this will mean albums, as by this time, singles were only promotional tools for albums, so weren’t kept in catalogue after they sold out. If that fails…
Contact the record label
You could try contacting the record label, if it’s still going. Who knows, if you’re lucky, you may get a replacement, at least in the form of digital files (yes, I know CDs are digital!)
CD reissues on other labels/non-UK pressings
Many of the affected titles have since been reissued by other labels, and many include bonus tracks from associated singles. Or you could try and find a second-hand copy of the title from another country.
Some of the affected music will have been re-released in a piecemeal fashion here and there: tracks on compilations or in expensive box sets etc. These will often be the well-known or particularly influential tracks, meaning that the B-sides, remixes and live tracks from CD singles will have been passed over.
Downloads or streams
Some of the affected music has since been made available as downloads or streams. This only really applies if the record label is still in business, or if another label has licensed the music. Anyone who bought obscure CDs on obscure labels that have now been out of business for decades will be out of luck in many cases.
So the music is often gone forever. As stated above, PDO manufactured CDs for lots of small, lesser-known labels, including bedroom outfits. While some of this music will have been recognised as being seminal or influential, and have been reissued by other labels, a lot hasn’t. In such cases, the only way to get another CD of this would be secondhand copies. You’d therefore be buying a pig in a poke, as there’s every chance that the replacement could also be affected.
If buying on Discogs, or from a friendly local dealer, you could ask the seller to either check the CD plays properly (time-consuming and probably impractical) or check they’ll refund you if you have any problems with it. (I’ve had mixed mileage with this technique.)
You will of course be able to find copies of some of the affected titles on vinyl or cassette. However, by the turn of the 1990s, vinyl was very clearly on its way out, and so lots of labels released their music as CD only. But as vinyl is now enjoying a boom, some of this music will now be available on vinyl for the first time. With any luck, you’ll be able to swap the crackles caused by PDO disc bronzing for the ones inherent to the vinyl format!
CD bronzing – conclusion
So there you have it. An annoying problem for music lovers of a certain age, especially those in the UK. But also for those who lived elsewhere, and who bought lots of CDs as British imports. A remedy was available for people who were aware of the company’s replacement scheme at the time, and who fastidiously checked their CDs not only once, but regularly throughout the period the scheme was in operation. Otherwise, we’re stuck, and have to try and track down cherished items from our music collection once again, many years after they were released. In some cases, this just isn’t possible. The CD bronzing problem has rendered some of our favourite music – and OK, probably some stinkers, bought on the off-chance – completely unplayable. Bah!
All photos © musicstuff.info