14 Mar
2005
14 Mar
'05
4:46 p.m.
Eric asks about writable DVD media:
why do the edges get attacked first? Are the disks
slapped together in some sort of fashion such that there exists a
potential breach at the edges?
Yes. They are laminated with adhesive, just as laser videodiscs were.
The adhesive leaks O2 even when it's working well, and as it degrades
it leaks worse.
Laser videodiscs have higher mass, so the problems occur faster, but
there's no reason to expect that the same problems won't happen to
DVD media. With laser videodiscs, the problems do start closer to
the outer edge, but they very rapidly (in a few weeks to a month)
progress to affecting the entire disc. I expect that DVDs will
behave similarly, though not quite as quickly. So not using the
edge will gain you a little, but not a lot. Not enough that you
should reduce your concern by any significant amount.
Eric