CD and DVD Media Quality

Back in the 80's, when the first CDR discs became available, the manufacturers stated that the data life on the recordable CD was in excess of 40 years. In the 90's when DVD media became available, the manufacturers said that the data life would be at least 100 years. Quite how they know that we don't know, however there have been a few occasions recently when the media have published scare stories about CD or DVD failure that will destroy your information 2-3 years after it is written.

In 2003, it is believed that more than 7,100 million CD-R and more than 400 million DVDR discs were manufactured sold and it is worrying that this media is being used to archive virtually everything. If these discs are the only place that you have priceless, irreplaceable, family photos and videos, company data and other important information, it is very concerning.

So What Are The Facts?
Generally, people who burn a disc without producing a coaster believe they have quality media. Unfortunately that only tells you the disc will be compatible (able to be played) in the vast majority of CD or DVD players. More importantly all better quality CD and DVD burners include technology called overburn/underburn protection making coaster production a thing of the past. Given the large quantities of B, C, D, E and even F grade media available on the market this would be quite worrying huh?

Have I Got Good Media?
There are only two foolproof ways of proving the data life of the discs you use:

Option 1: Write some CDR or DVDRs, then wait about 25-50 years and check if they still hold the correct data
Option 2: Use a CD/DVD analyzer that is specially designed to retrieve very accurate information about your media and your data after accelerated aging in test chambers where the discs are subjected to excessive temperature and humidity tests

The first is impractical however some of the first discs produced and written to in Japan still hold valid data. The second provides only theoretical limits and doesn't’t take into consideration how you use, handle and store the media.

Between the CD-R discs produced in the early 80s, to today’s double layer DVD+R DL discs there has been considerable progress in write performance, capacity, quality and obviously price. Through using the test procedures of the International Standards Organization, quality media manufacturers have been able to document data life-spans ranging from 50-200 years. Please bear in mind there are massive differences between low budget media operations and quality media manufacturers. In addition variations in manufacturing methods, materials and processes/procedures can dramatically affect the data life of the media you use.

Understanding CD and DVD Media Construction
It isn’t vital that you understand the construction of CDR or DVDR media to produce a quality disc that can be read years from now anymore than you need to understand the internal combustion engine to drive. Understanding the difference between quality and cheap media may help you avoid losing data later on.

Most people consider DVDR discs little more than overgrown CDR and while they are similar, they are also quite different.

Writable CD and DVD discs start with a piece of polycarbonate substrate onto which very precise grooves are molded. A dye layer is then precisely applied to the substrate followed by a reflective layer and one or more protective layers. A few of the media leaders have initiated the policy of applying two very resistant layers for added data protection when the discs are used, handled and stored.

Because of the faster read/write performance users expect, the leading manufacturers have developed new stamper technology for optimum groove shape and ultra-precise molding technology. The molding is critical because disc flatness is extremely important when the media must be rotated at extremely high speeds – 52x for CDR and 16x for DVDR.

Media Problems
The quality of your media is directly proportional to the time the media will last without losing information. As you can see from the manufacturing process, there are a number of areas where manufacturers can shave a few pence off the overall cost of the disc.

There are also confusing and conflicting claims and consumer beliefs as to which media is best for data retention of 30, 50, 100 years – green, gold, blue dye or gold/silver reflective layer. It is somewhat immaterial today. Leading manufacturers such as Ritek and Traxdata have developed advanced, stable and reliable dyes and reflective materials that will virtually eliminate data loss during the high-speed read/write processes and subsequently enhance longevity.

One of the most common causes of problems are delamination and oxidation, which usually occurs at the outer edge of the disc and is often the result of the adhesive not being properly applied and cured during the production process. This usually happens when manufacturers use equipment that is 2-3 generations old and the least expensive materials possible to produce the cheapest discs.

Take Care of Your Media
Even if you have purchased quality media from a quality manufacturer, you are still not assured of 50-100 years of data life! Humans are the greatest danger to long term data on a CD or DVD; exposure to sunlight and heat can do dramatic damage and changes in temperature and humidity can stress the materials.

We have put together a few tips for handling media:

What you can do:

• Handle discs by the outer edge or the centre hole
• Use a non solvent-based felt-tip permanent marker to mark the label side of the disc (always in stock)
• Keep dirt or other foreign matter from the disc
• Store discs upright
• Return discs to their jewel cases immediately after use
• Leave discs in their spindle or jewel case to minimize the effects of environmental changes
• Remove the shrink wrap only when you are ready to record data on the disc
• Store in a cool, dry, dark environment in which the air is clean -- relative humidity should be in the range 20% - 50% (RH) and temperature should be in the range 4°C - 24°C
• Remove dirt, foreign material, fingerprints, smudges, and liquids by wiping with a clean cotton fabric in a straight line from the centre of the disc toward the outer edge
• Check the disc surface before recording

Do not do this...

• Touch the surface of the disc - ever!
• Bend the disc
• Store the disc horizontally for a long time
• Expose discs to extreme heat or high humidity
• Expose discs to extreme rapid temperature or humidity changes
• Expose recordable discs to prolonged sunlight or other sources of UV light
• Write or mark in the data area of the disc (area where the laser "reads")
• Clean in a circular direction around the disc.

You Want Reliable Media?
There is a lot of cheap CDR and DVDR media that has marginal quality. It may work for data and then not for video. For some applications like games, quality isn’t critical. For irreplaceable, vital data like family photos, special events, vacations and family/friends memories quality does matter. If you are backing up mission critical data on your home or business computer, quality definately matters. Then it is important to select a brand of media that will keep your data safe, secure and available for years to come.

We at BBDiscs only sell GRADE A media from leading manufacturers such as Traxdata, Verbatim, Taiyo Yuden, Ritek and TDK. We do not import cheap media from the far east and buy either direct from the manufacturer or from an authorised distributor. We are not the cheapest around, however we are the most reliable. Take a look at our store for more information on the products that we have available right now.

Thanks for reading, if you have any questions on this article please drop us an email.