The best CD labeler for preventing the early degradation of CDs, DVDs, and other optical disc media is a CD marking pen in the form of a water-based permanent felt tip marker. When it is necessary to label a CD or DVD (usually a recordable or erasable disc) to identify the contents on the disc, then it is important to do so in way that will minimize damage to the disc in the short and long term.
Writing on the disc is the easiest, quickest, and most inexpensive method to label optical discs. A CD or DVD marking pen should not contain any solvents. It should be water based; otherwise pens containing solvents can damage layers of the disc. A felt tip permanent marker is best. No pens, pencils, or markers should be used that require a lot of pressure to write with. Pressing down on the top surface of discs, especially CDs will damage the metal layer in the disc and cause problems when the disc is read or played.
It is difficult to determine if a CD labeler marking pen is water based and just because it is labelled or recommended as a CD pen or DVD pen does not mean it is safe to use. No research has been performed to investigate various CD marking pens and there are no standards for CD pen manufacturers to conform to.
Because of the uncertainty as to whether pens contain harmful solvents, the uncertainty as to the reactivity of the inks towards the disc layers, and the potential damage to the layers of a disc by using too much pressure to write, the location of the disc labeling needs to be taken into consideration. For maximum disc longevity and maximum safety when using a CD marking pen as a CD labeller, it is best to only write on the hub portion of the disc. In most cases, the hub portion is clear, but sometimes some of the disc labeling applied by the manufacturer is spread across the hub. Regardless of whether the hub area is clear or not, the key is that there is no digital information stored in this area and therefore, if the marker does contain solvent and is chemically active, the stored digital information will not be affected. Also, using pressure to write on the CD with the CD marking pen will not damage the metal layer and cause any disc play problems when labelling is performed in the hub area.
The problem with labeling in the hub area is space. It is impossible to write a long descriptive sentence about the disc contents in such a small area. Descriptions need to short. An alternative is that a code can be written and cross-referenced to a database with more descriptive information. Although this is not ideal because you cannot immediately identify the disc contents it is a good alternative when the CD label needs to be more descriptive than just a few words.
In summary, the safest CD labeler method for CDs, DVDs, and Blu-rays, is to write on the hub area of the discs with a water based felt tip permanent marker. Following this labeling recommendation will ensure that no damage to discs occurs now and in the future.