Various Formats of CD-ROMs

Lunicus CD-ROM by Cyberflix Interactive, Inc. (1993)

This is the oldest CD-ROM in the set. The front is silk screened in black-and-white. This conventional foil CD-ROM exhibits strong lighting bolt patterns, with multiple levels of forking. This (along with that shown on the Microwaved AOL CD-ROMs page) is typical of the kind of patterns seen on all commercial CDs and CD-ROMs.

Sony Blue-Green 650MB CDR

This is an old CDR, with blue-green organic dye. The CDR was apparently either exposed to adverse temperatures at some point or was simply breaking down with age. The dye was found to be discolored when the CDR was initially used, rendering it unusable.

After microwave cooking, the CDR exhibited unusually wide lightning bolt patterns, with multiple levels of forking. Large amounts of foil burned off during the microwaving process, exposing wide swathes of the organic dye layer. The remaining foil easily flakes off of the disc.

Maxell Blue 74 Minute Music CDR

This is a newer CDR with a blue organic dye. It shows lightning bolt patterning with multiple levels of forking. This CDR showed several unusual markings:

Several of the lightning bolt patterns intersected areas of foil left exposed by the silk screening on the front surface of the disc. In these cases the lightning bolt constrained itself to the lines of exposed foil, following it for a centimeter or more. (These lines are approximately 30 degrees off of vertical in the picture above.) There were several points where the end of a lightning bolt pattern fanned into a dense grouping of forks. The reason for these groupings is unknown. They do not seem to correspond to any surface irregularities or markings on the silk-screened front surface. They appeared in no other instances. In areas where the bolt patterning was especially thick (indicating strong currents with correspondingly higher temperatures), the organic dye was discolored and changed thickness. This shows up as areas of distortion surrounding the trunks of the lightning bolt patterns.

Memorex Silver-Green 700MB CDR

This CDR uses a silvery green organic dye. It exhibits almost no lightning bolt patterning, and few wandering lines. Instead, it shows very strong concentric arcs and radial line patterns. This divides the surface into a distinctive mosaic pattern. It seems almost certain that this CDR employs a grooved plastic disc substrate, instead of the flat disc used by commercial pressed CDs and CD-ROMs (as well as the older CDRs shown above). Newer CDRs are impressed with a continuous smooth spiral groove running over the writing surface. This groove serves to guide the CDR drive during the write process. The groove constrains the lines burned into the foil to strong concentric arcs, placed where the foil is deformed across the surface of the spiral groove. Current jumps in radial lines between these arcs. This mosaic pattern appears to be unique to CD media pressed with a continuous spiral guide groove.

Memorex Silver-Grey 650MB CDRW

This CDRW uses a silvery-grey dye. It exhibits mosaic patterning, indicating the presence of a continuous spiral groove in the plastic substrate. However, it also shows small, multi-forked lighting bolt patterns rooted in the concentric arcs and radial lines. The front surface has a minimum of paint, only a light frosted effect with the text picked out in exposed bright foil. It is possible that this is the reason for the additional lighting bolt effects. There are also a few points where the burned patterning is constrained to straight lines, due to the presence of these lines of exposed foil on the front surface. It is interesting to note that this constraining effect only happens with long, straight lines, and not with oddly shaped areas of exposed foil.

Sony Playstation Pizza Hut Promotional Game Disc One (1999)

Some console game systems use game discs with translucent black plastic substrates, as a protective measure against software piracy (so-called "black encryption"). Most computer CD-ROM drives cannot read through this plastic. Otherwise, though, the discs use an impressed plastic and foil system just like regular CDs. When exposed to a strong back light, lightning bolt patterns similar to those present on most microwaved commercial CDs can be seen.

This particular disc was also used as a game piece. The disc was to be held up to the light, and the results read through the hub. This one was not a winner.

Promotional DVD, Origin Unknown

This is a dual-sided DVD, presumably with different content on each side. Unlike normal CD-ROMs, the foil is sandwiched between two layers of clear plastic substrate, instead of under a painted front surface. Displays unusually strong lightning patterns with minimal forking. This experimental run was different from the others, in that an unusual amount of heat was retained in the disc. After exposure, the disc was hot to the touch and slightly tacky.

Nothing is known about the origin of this disc. It was purchased, along with several music CDs in a bundle, at a garage sale in late 2001. The label on the hub appears to have been deliberately defaced by the previous owner. The disc would not play in any available DVD players, indicating that it might have been recorded in a foreign regional format. Now that the DVD has been destroyed, it seems unlikely that this mystery will ever be solved.