The easiest way to label a CD-R is to whip out that permanent marker and write directly on the disc. It's also a great way to assure that the disc won't be readable later on.
The damage won't happen today, or even next month, but at some point the ink will leach into the reflective layer of the disc and it'll be the end of your data.
Now, we're not saying you can't label your discs. But you do have to be careful of the kind of writing instrument you use to do so. In order to understand why certain markers and pens can harm your CD-Rs and DVDs, we first need a basic lesson on the physical properties that make up the disc:
CD-Rs and DVDs are made mostly of polycarbonate substrate, or plastic. The plastic is there to carry the data layer - the shiny metal you can see when you look at the bottom of a disc. The data appear as marks or pits that either absorb light from the laser beam or transmit the light back to the laser/photosensor by way of the shiny metal reflective layer.
Most people know that it is very important to keep the bottom of your discs clean and scratch free. Scratches, fingerprints, and other debris can stop the laser from reading the data.
However, most people don't realize that the tops of discs are just as prone to damage as the bottom - if not more so! Although you can physically see the shiny data layer from the bottom of a CD-R, it is actually applied to the TOP side of the disc, just under the label. On some CD-Rs, the data layer is under nothing but a thin layer of lacquer. Damage to the top of the disc can destroy the data all together.
There are a few side notes that we cannot ignore here: The first being that CD-Rs and DVDs are constructed differently. The data layer in a DVD is more protected than that of a CD-R. However, this does not make it immune to damage.
Second, it should go without saying (but we'll say it anyway) that you should never write on or label a double sided DVD - since both sides are read by the laser.
Last, some CD-Rs have additional protective layers on the top of the disc, for example those with a "white printable surface." These CD-Rs, while more expensive, are far less susceptible to damage.
So what harm will come from writing on discs? Obviously, ballpoint or hard tipped pens can scratch the surface of the disc where the data reside, possibly rendering it unplayable. Anything that puts high point-pressure on the surface can damage the delicate layers beneath. Although this might not happen every time, it would be worth not taking the risk.
But what about those soft tipped permanent markers that everyone uses? Can those cause harm, too? Possibly. The tip won't harm your disc, but the ink might.
There is growing concern that components of ink from markers previously thought of as "safe," such as many commonly used permanent markers, will eventually penetrate and be absorbed by the inner layers of your disc, damaging the surface where the data is stored and rendering the disc unplayable.
Use of permanent markers
Various postings are surfacing across the internet from professionals and hobbyists alike, reporting that over time permanent ink has made their properly stored discs unusable. There is no apparent reason for the corruption other than the ink used to label the disc.
So what should you do? Consider the purpose of the disc. If all you're doing is making a music disc for your car, it really doesn't matter. You'll have a new favorite band before the ink has time to ruin it. However, if you are archiving precious family memories or other highly important data, don't write on top of that disc!
Instead, label the disc where no data is recorded. The inner hub area, though small, is a perfect location for labeling.
Alternatively, if you didn't use the entire capacity of the disc during recording, you can write in the area that wasn't burned. Discs are written from the inside out. The area that was recorded is darker. The lighter area wasn't recorded and has no data, so it's safe for labeling. But, be careful that you don't cross over the line and into the data (see illustration). Note: Don't do this with rewritable discs.
Write in the area that was not burned
If you really want to be safe, use a specially formulated disc marker. It contains ink specifically made for labeling the tops of CD-Rs and DVDs.
What do I do if I have already labeled my discs with a permanent marker? Transfer the data to a new ink-free disc as soon as possible.
Don't even think about trying to remove the ink. Permanent ink and the soft porous resin of a disc are quite happy together, and don't want to be separated. Attempting to remove the ink will most certainly ruin the disc.
According to the National Institute of Standards and Technology (NIST), a properly cared for disc which is stored under recommended storage conditions can have a very long life expectancy. NSIT's research has concluded that CD-R, DVD-R, and DVD+R discs should have a life expectancy of 100 to 200 years or more. CD-RW, DVD-RW, DVD+RW, and DVD-RAM discs should have a life expectancy of 25 years or more. Less testing has been done for CD-ROM and DVD-ROM discs, however lifetime expectations vary from 20 to 100 years for these discs.
One thing is certain - proper care of any disc will extend its life.
Comments?
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