James Perrett wrote:Is this replacement a commercially made pressed CD or a home burned CD? A cassette is likely to be playable for longer than the average home burned CD.
It is a home burned cd, that I thought lasted way longer, than home made cassettes? You know way more about this than I, but I thought some cd's could last forever?
Regular, read-only CDs store information by physically burning the pits and then covering the thing in plastic. So if properly stored (no scratches) it will last practically forever - it's like etching writing in stone and then protecting it from the elements.
A CD-R uses dye instead, and the problem is that all dyes are more or less susceptible to fading (and much more so if exposed to light). That's why they degrade. The ones with gold reflective surface and a specific class of dyes (dont recall the name) tough last very very long if they are kept mostly in the dark.
A CD-RW uses a sliver alloy which "phase changes" from crystalline (reflective) to amorphous (non-reflective) when heated up a lot over a short time (high power), and can revert again to crystalline if, in amorphous state, is heated up a little over a longer time (low power). The heating is done by the writing laser in both cases.
Without going into details this is a more hazardous process because of the disk material and its phase stability in the field and the necessity of very precise laser power control to minimize degradation when reading.
So a good CD-R, well packed so light does not reach it and not subject to temperature swings can last quite a bit. A CD-RW, if you burn it once and you plan to read it once or twice (for example to image it into a different medium) it can.. but it's a bit of a lottery.