Volume 18, Number 6
Oct 1994

Marking CD-ROMs

Reprinted with permission from an October 14 posting on the Conservation Distribution List, where it appeared in response to an inquiry from a librarian with a growing CD collection. Jim Lindner is the author of "Confessions of a Videotape Restorer; Or, How Come These Tapes all Need to be Cleaned Differently?" which appeared in the AMIA Newsletter for April 1994 and which was cited in the August-September issue of this Newsletter on p. 61. His company's name is Vidipax, and the helpline number is 800/653-8434.

There are several different types of disks that are generally called CD-ROMs, including:

CD-DA
CD-ROM
CD-R
CD-ROM XA
Photo CD
CDI
Laserdisks
and others.

It is very important to pay attention to the manufacturers' recommendations for these different media types. Although CD-ROMs may look the same, the physical construction may be very different due to the capabilities of the system. For example, recordable CDs (there are several kinds) have a composition that will allow data to be recorded on the disk, and therefore are generally more fragile than the typical music play-only versions mastered in large plants. These different media have different layers and composition, so that it is possible to use a chemical that could over time damage a protective layer.

Most "commercial" CDs that are duplicated in a large facility have a very thin layer of varnish that separates the aluminum disk from the printing on the top of the disk. The duplicating industry has had considerable discussion lately on the types of inks used in production (it seems that some inks can cause problems over time). In general, one should never use a ballpoint pen or any writing implement that will cause any physical pressure to be placed on the disk. A felt tip marker should be used, and in the case of recordable CDs write only in the area designated for the writing.