[filmscanners] RE: How to label CD backups

["Cliff Ober" <cdober@ev1.net>]

Over the years I have OFTEN seen the ink from Sanford Sharpie pens
absorbed into plastic materials on which information had been written.
Test for yourself - write with a Sharpie on a variety of plastic
materials, then wait six months or so and try to clean it off. On a
number of different types of plastics you'll find the ink has literally
diffused into the plastic. My wife takes advantage of this to label
Tupperware (polyethylene) containers that she loans out on occasion -
the diffused name label can't be cleaned off and invariably results in
the return of the container (usually with some kind of goodie in it!).

I have never seen diffusion into polypropylene materials, but I do know
that PVC (vinyl) and polyethylene will absorb the ink dyes.

Someone mentioned the permanence of the Sharpie ink; there is now
available an industrial version of the Sharpie that has what Sanford is
calling "Super Permanent" ink. It appears to have both dye and pigment
in it, and it is much more durable than previous inks they've used. I've
been seeing the new pens at Wal-Mart; they have the medium size felt tip
and sell for a slight premium over the original pens.

Cliff

-----Original Message-----
From: filmscanners_owner@halftone.co.uk
[mailto:filmscanners_owner@halftone.co.uk] On Behalf Of
david_bookbinder@sprynet.com
Sent: Monday, November 04, 2002 11:40 PM
To: cdober@ev1.net
Subject: [filmscanners] Re: How to label CD backups


I'm somewhat puzzled by the proscription not to write on CDs with
markers such as the Sharpie, which use some kind of non-alcohol solvent.
As I understand it, the CD is a thick layer of plastic, a thin layer of
dye, a thin layer of metal, and a thin layer of lacquer to protect the
metal. A solvent-based marker could, perhaps, soften or slightly deform
the layer of lacquer (until it hardened again), but I don't see how that
would affect the metallic layer beneath, or the dye layer beneath that.
If the dye layer and the metallic layer are unaffected, what is the
presumed risk of using these commonly available markers? Unless the
marker completely exposed the metallic layer or scratched it, once the
marker dried, there would once again be a layer of lacquer protecting
the metal, which in turn protects the dye.

- David


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