Frequently Asked Questions About CD-R and CD-RW Discs

Please contact Media Sciences if your questions are not answered on these pages.

Is it safe to use marking pens on CD-R discs?

Controversy exists about the use of marking pens, and the answer depends both on the application and on the specific media. Of course, write only on the label side, never on the readout surface. Do not write using a ballpoint pen or other object having a hard point. CD discs have a soft, very thin protective coating on the label surface that is vulnerable to chemical or physical attack.

The safest method of identification is to rely on the manufacturer's lot code that is present on the clear inner ring of the disc. Small, custom markings in this area can be safely made with felt-tipped marking pens that use water-based inks. Such pens may be available from CD-R manufacturers, or the Dixon Redisharp Plus! can be purchased at office supply shops.

Popular felt-tipped pens, such as the Sharpie, use solvent-based inks. The solvent can attack certain CD protective coatings, causing degradation that may not be immediately apparent. Even water-based inks may not be safe, since the permanent ink from any marking pen can subsequently degrade the information layer.

Predictions of longevity for CD-R discs containing label-area markings is difficult because of many variations in the manufacture of these discs. Various dye types and metallizations may interact differently with markers. Protective layers were initially solvent-based, but UV curable coatings are used more frequently because cure times are shorter. Resistance to solvents and inks of each coating type can differ. Discs having various types of hard overcoats and printable surfaces are available, some of which offer additional protection while others do not, or may even degrade longevity.

A brief study by Media Sciences used various CD-R discs that contained both Sharpie and Dixon Redisharp Plus! markings on the label surface. All discs degraded after accelerated aging for 100 hours at 60°C and 85% relative humidity, conditions that are within allowable limits for CD-R discs. Degradation often resulted in uncorrectable E22, E32, and BURST errors. No single media type or specific marking pen was consistently better than another.

Results indicate that markings in the label area should be avoided when longevity is important and interchange after at least 20 years of storage is critical. Marking pens can be used successfully if short-term longevity is acceptable and discs are stored under cool, dry conditions that slow down chemical reactions. Pens containing solvent-based inks may be satisfactory with some discs, but water-based inks are always safer.

Most inks used for screen printed labels on CD discs have been carefully tested. Marking pens have not been subjected to the same qualification by their suppliers, and present a very real risk when CD longevity is important. Lifetimes of discs identified using marking pens are unpredictable pending comprehensive test results from their manufacturers.