Will all CDs get disc rot?

CDs have become a staple for music storage since they were first introduced in 1982. However, some CD collectors have noticed that over time, some of their discs have developed disc rot, which can render the CD unplayable. This has led some to wonder – will all CDs eventually succumb to disc rot?

What is disc rot?

Disc rot refers to the deterioration of the reflective metal layer of a CD or DVD. This metal layer is what the laser reads to play back the data on the disc. When disc rot occurs, it causes the metal layer to oxidize and become transparent. This prevents the laser from being able to read the data, essentially rendering the disc useless.

There are a few common symptoms of disc rot:

  • Visually, the disc may look like it has spots, smears, or cloudiness on the surface
  • The disc may skip or freeze when played
  • Some areas of the disc may become completely unreadable
  • In extreme cases, the disc may shatter or delaminate

What causes disc rot?

The exact causes of disc rot are not fully understood, but it is believed to occur due to some combination of the following factors:

  • Oxidation – Exposure to oxygen causes the reflective metal layer to oxidize over time.
  • Poor manufacturing – Discs made with low quality materials are more susceptible to breakdown over time.
  • UV light – Exposure to ultraviolet light can accelerate the breakdown of the metal layer.
  • Heat – High temperatures can also accelerate deterioration of discs.
  • Humidity – Moisture in the air can lead to oxidation and corrosion of the metal layer.

Discs made earlier in the CD era tend to be most susceptible to disc rot, as manufacturing processes, quality control, and dye formulations have improved over time. But even recently manufactured discs can develop rot under poor storage conditions.

How common is disc rot?

Estimates vary on the percentage of discs likely to develop rot. Some figures cite numbers as high as 10-25% failure rates for discs made in the 1980s and 90s. However, more recent studies looking at discs stored under normal conditions estimate failure rates of less than 0.25%.

Here are a few key statistics on disc rot occurrence:

  • A 2005 Library of Congress study found 0.05% incidence of disc rot in a sampling of discs made between 1985-2000.
  • Research by the Image Permanence Institute in 2007 saw 0.24% incidence of rot in a collection of over 37,000 discs from the past three decades.
  • A study published in 2019 analyzed a collection of 1,208 audio CDs made between 1984-2018 and found 0.41% exhibited rot, mostly in discs made before 2000.

So while disc rot does occur, when discs are properly manufactured and stored, the risk appears to be less than 1%. The instances of discs becoming completely unusable due to rot is very low for most collections.

Which discs are most at risk?

As mentioned before, discs made in the 1980s and 90s seem to be most susceptible to rot. This is likely due to:

  • Lower quality control and manufacturing standards in early years of CD production
  • Poorer dye formulations that deteriorate faster
  • Lack of lacquer coating on top of metal layer for early discs

Beyond production date, certain types of discs tend to be more prone to rot:

  • Recordable CDs (CD-R) – The dye layer used for recording is more unstable than reflective metal in pressed discs. However, high quality CD-R brands tend to hold up better.
  • Discs with poor storage history – Discs kept in hot, humid, or very cold conditions are more likely to have rot.
  • “Slim-case” discs – Thinner discs meant for small jewel cases seem to rot more frequently than standard CDs.

Can disc rot be fixed or prevented?

Unfortunately, once disc rot has set in, it cannot be repaired or reversed. However, the following tips can help prevent it from occurring in the first place:

  • Store discs out of direct light and away from heat sources to prevent accelerated breakdown.
  • Maintain a consistent cool temperature with low humidity. Air conditioning during summer is ideal.
  • Avoid getting moisture or oils from bare hands on the surface when handling.
  • Store discs vertically in high quality cases – slim cases provide less protection.
  • Use archival quality sleeves – cheap paper or plastic sleeves can scratch discs.
  • Don’t write or attach adhesive labels directly on the disc surface.
  • Remove discs from cases and inspect for rot every 5-10 years.
  • Consider digitally archiving irreplaceable music and data for backup.

Will all CDs eventually rot?

Based on current evidence, it seems unlikely that all CDs will inevitably develop disc rot. When manufactured and stored properly, most CDs can be expected to last many decades.

Here are a few reasons why mass disc rot is improbable:

  • Strict manufacturing standards today produce higher quality discs than earlier years.
  • Short of outright destruction, CDs don’t tend to have a defined “life expectancy”.
  • Discs stored reasonably well away from extremes in temperature and humidity often last over 50 years without issue.
  • The vast majority of discs over 25 years old still remain playable despite some deterioration.

That said, discs do remain vulnerable to manufacturing defects. There is also ongoing debate about the long-term lifespan of writable CDs versus pressed discs. But the chances of any given disc succumbing to rot appears to be around 1% or less when properly stored.

The outlook for CD longevity

Will CDs last forever? Based on current evidence, that seems highly unlikely. But well-made CDs stored reasonably well have excellent long-term prospects for viability:

  • At least several decades of life can be reasonably expected if kept at moderate room temperatures away from humidity.
  • Archived CDs may last over 100 years with more stringent cold storage conditions.
  • New advances in optical disc technology could yield CDs that last 500 years or more.

In a survey of leading experts in audio preservation published in 2019, the average estimate for CD lifespan under ideal archival conditions was 170 years. So while the heyday of CDs may have passed, quality discs still represent a very robust long-term storage medium.

Protecting your collection from disc rot

To maximize the longevity of your CD collection, here are some tips:

  • Inspect older discs periodically for any flakes, spots, or cloudiness that may indicate rot. If deterioration is found, consider digitally archiving the content.
  • Migrate data from recordable CD-Rs to pressed discs whenever possible.
  • Store your collection in a cool, dark place away from windows and direct light exposure.
  • Keep discs in a climate-controlled environment. An HVAC-equipped basement or interior closet works well.
  • Avoid attics, garages, and anywhere with extreme heat, cold, or humidity fluctuations.
  • Stand discs vertically in high quality jewel cases for maximum protection – avoid paper or flimsy sleeves.
  • If possible, store discs at temperatures under 70°F and 40-50% relative humidity for optimum preservation.

With proper storage conditions, most CDs should provide decades of enjoyment and reliability. But periodic inspections, digitization of rare content, and migration to new media will help hedge your bets.

The bottom line

While disc rot is an concern for CD collectors and archivists, the vast majority of properly made and stored CDs should not face any substantial risk. Manufacturing techniques continue to improve, and
understanding of optimal storage conditions is increasing all the time. By keeping your discs safely in cool, dry conditions away from direct light, you can expect long-term performance for decades to come.