[filmscanners] RE: CD Labeling and alcohol

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

The other day I mentioned the diffusion aspects of the Sharpie inks with
plastics; I took a look at some Memorex CD's I wrote about a year ago
and marked on in the white label area with a medium point Sharpie (these
are short-term backup CD's not archival stuff). The marker ink has
visibly diffused into the white label "paint" or lacquer coating. The
disks have not yet exhibited any problems with data loss, but I sure
wouldn't want to trust marking on important CD's after seeing this...
(not that I'd use Memorex for anything really important anyhow).

Cliff


-----Original Message-----
From: filmscanners_owner@halftone.co.uk
[mailto:filmscanners_owner@halftone.co.uk] On Behalf Of
david_bookbinder@sprynet.com
Sent: Friday, November 08, 2002 9:54 AM
To: cdober@ev1.net
Subject: [filmscanners] RE: CD Labeling and alcohol


At the risk of beating a dead horse, just for kicks I filled a the
cheapest CD-R I had (a Kensiko) with data, made a copy of the CD, then
scribbled on the first CD with three Sharpie markers. I covered the top
third with a Liquid Sharpie, the bottom third with a Fine Point Sharpie,
and the middle third with an Ultra Fine Point Sharpie. I covered these
surfaces three times, scribbling horizontally, vertically, and at a 45%
angle.  Then I let the inks dry for several minutes and compared the two
CDs. There were no detectable errors on the "Sharpied" CD-R.

I can believe that using archival envelopes is about as safe a way of
preserving CDs as there is, but I don't know where the notion, as noted
below, that the "alcohol eats its way through the plastic and attacks
the metal" comes from. No lacquer I have ever encountered is soluable in
alcohol. As another test, I soaked a pad with isopropal alcohol, pressed
it to the lacquered surface of a CD-R with a metal plate, covered the
whole thing with a cereal bowl to delay evaporation, and left it
overnight. The next morning, there was no visible evidence, under a
loupe, that the alcohol had done anything at all to the lacquer coating
of the CD. A brisk rubbing of the alcohol-covered surface revealed no
softness or stickiness, either.

I will continue to repeat the comparison of the "Sharpied" CD and the
copy over time, to see if there is some insidious effect that the
long-evaporated alcohol has on the lacquer or the underlying metallic
coating. But I am hard-pressed to see how an alcohol-based pen like the
Sharpie, whose volatile compounds evaporate in seconds, could ever
damage a CD. Has anyone ever done any actual testing of this theory, and
if so could you point me to the documentation?

Thanks,
David


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