The
top plastic layer on a pressed disc is pretty sturdy - not as
durable as the thicker bottom layer, but pretty good especially when
it has a nice coat of silk-screen ink on it. An erasable is usually
pretty good in this respect as well; not as resistant to mistreatment
as a pressed disc, but a lot better than a typical CD-R. A write-once
blank may have a durable top surface added or not. A durable surface,
like one advertised for 'long life' or used to support ink-jet
printing, is still much more vulnerable to scratches than is the top
of a pressed disc, but the least expensive blanks, with no additional
protection or surface printing, are the most fragile of all.
In general, if you
want to write onto an uncoated disc, you should use a pen made for
the purpose. TDK has one available for about $3. Many uncoated discs
will take writing from the felt-tip (not the metal-sheathed
ultra-fine) Sharpie, but there is a slight risk that the solvent in
the Sharpie's ink can etch some plastics which may be used. Other
pens may well be safe, but why not hedge your bets and either find
out from your medium's manufacturer or stick with something made for
the purpose? As for pencils and ballpoints: you might as well use a
dentist's drill or a sandblaster.
Another option is
to apply an adhesive-coated paper label such as are available from
Avery, Neato, Stomper and others. That's a fine solution, but there
are some risks. Obviously, the label needs to be pretty well centered
to avoid problems in high-speed readers. Also obviously, you don't
want loose adhesive to foul up your reader or its optics. However,
the biggest problem is the adhesive used. It must not let go. If it
does, the label will peel away in part, snag in the drive and
potentially peel some of the adjacent plastic layer. And that is
disaster. If you scratch the thick layer moderately, there will
probably be no effect at all. But an uncoated disc has a remarkably
thin upper layer and even a tiny scratch or hole will disrupt the
metal layer below; a disturbed reflecting layer means no reflections,
which means no data - dead disc.
|