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knowing what you are buying

Silver Reflective Layer for Superior Performance

Silver Reflective Layer for Superior Performance

Significant performance differences between silver and aluminum reflective layers highlight the importance of knowing what you are buying.

The material used for the reflective layer of a blank CD or DVD is a critical factor in the disc failure rate. The layer reflects the laser beam back to the laser photosensor in the laser head, so if this reflection is not precise and consistent, the disc will have errors when writing or reading data.

The reflective layer is generally made of aluminum or silver. Discs with aluminum reflective layers are generally cheaper, while silver layers offer superior reflectivity, which can improve reading and writing performance. It is necessary to understand the importance of these performance improvements and whether they justify the price difference.

Additionally, in the evaluation, it is necessary to note that the lasers in optical drives deteriorate over time and become less powerful. It is therefore relevant to understand how optical discs perform in relatively new drives and in older ones.


In tests with new optical drives (less than one year old), the failure rate in burning content to aluminum discs was over 10% for DVDR and over 13% for CDR, compared to zero failures for silver. However, when used in older optical drives (over one year old), the burning failure rate was significantly higher - over 15% for DVDR and over 25% for CDR, again compared to a zero failure rate for silver. Furthermore, in the error rate tests, all silver layer products performed within specifications (DVD: PI sum8<280 and CDR: C1<220) while all aluminum discs were out of specification, with significantly higher errors recorded in tests on optical drives over one year old.

These performance differences can be directly attributed to the lower reflectivity of the aluminum layer compared to silver.


Optical media are also susceptible to corrosion, particularly during shipment by sea where they can be exposed to high temperatures and humidity. Aluminum oxidizes upon contact with oxygen from the environment or with moisture that penetrates the disc, reducing its reflectivity and making the disc unreadable by the laser, a phenomenon sometimes called "disc rot". Silver can also lose reflectivity with corrosion due to exposure to sulfur dioxide, an environmental pollutant that can migrate through the disc with moisture. However, the Reliability Test showed that all silver products passed the 100-hour heat and humidity test, which verifies the endurance of exposure during shipment and storage as well as archival capabilities. In contrast, all aluminum CDs and DVDs did not reach the 100-hour mark.

TABLE - Defect Rates for Optical Media with Aluminum or Silver Reflective Layers

CD-R AluminumCD-R SilverDVD-R AluminumDVD-R Silver
Burn Failure Rate (Drive < 1 year)>13%0%>10%0%
Burn Failure Rate (Drive > 1 year)>25%0%>15%0%
Error RateAll out of specWithin book specAll out of specWithin book spec
Reliability Test (80°C/80%RH) – 100 hours (*Simulated for 1 year longevity)FailedPassedFailedPassed

Source: CMC Quality Comparison Test


When buying blank media, the material used for the reflective layer may never be considered, but it is clear from this analysis that it is a key attribute and should be part of the selection criteria. The lower reflectivity of aluminum results in significant failure rates in writing and reading, which worsen further with the use of older optical drives with weaker lasers. Aluminum discs also have higher corrosion issues, and another known problem with aluminum discs is that they become hotter during use, accelerating the degradation of the optical drive's reading head.

Therefore, when buying optical media, although there may be a small price difference, it is hard not to always choose silver.

Identifying Discs with Silver or Aluminum Reflective Layers

Left: Silver reflective layers are slightly transparent.
Right: The aluminum reflective layer is opaque.


  1. PI Error (PIE): A byte error occurs when one or more bits in a byte have an incorrect value compared to their originally recorded value. One row of an ECC block that has at least 1 byte in error constitutes a PI error. In any group of 8 consecutive ECC blocks, the total number of PI errors before correction must not exceed the book spec of 280.
  2. Reliability Test: The results represent continuous exposure to extreme temperature/humidity levels. Error rates are not representative of discs stored in typical, normal, or ideal conditions. These test results serve to demonstrate, in terms of error rates, the capability of some DVD and CD media to remain stable even when exposed to extreme conditions.
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