Mac Lab Report
Don't Use Sharpies on CD-R
Mike Webb - 2003.01.14
We received the following email from Mike Webb and present it as a guest column, since this seems to be an issue many computer users are unaware of. dk
I have just finished reading your article on how to make a bootable emergency CD for the Mac, OS 9 and below. While I found most of the article to be an invaluable resource (I've already printed it to PDF), there's one thing you mentioned at the end that does concern me.
The item which concerns me was your advocacy that we use Sharpie™ markers to label our CD-Rs. There is a modest amount of anecdotal evidence that the use of solvent-based ink markers (Sharpies use an alcohol-based ink), particularly on CD-R/RWs without a protective coating and CD-R/RWs kept in a warm to hot environment can lead to long-term penetration of the ink to the data layer with resulting damage to the data.
The primary source of my information is a post to a mailing list made by the director of a National Public Radio station, where he reports that this kind of thing had happened at several NPR affiliates. I have corresponded with this person, and he confirmed the content of the original post. What seems to have triggered the problem was that the CD-Rs were being placed in warm/hot CD players, cued up for broadcast.
In further researching the issue, I discovered that the standards organization for CD-R/RW media also advises that people use markers with permanent, water-based inks. They got their information going way back from Taiyo Yuden, one of the early manufacturers (and still a premier manufacturer) of CD-R/RW media.
There are a number of markers available for a reasonable price that use permanent, water-based inks. There are at least half a dozen brands of special "CD markers" on the market, and I've also had very good results with the Sanford Vis-a-Vis (permanent version), as well as a marker which has been recommended highly, the Dixon RediSharp Plus!
While the incidents seem to be widely scattered and infrequent, I prefer not to take chances with my data/music/etc. and stay with either the Sanford Vis-a-Vis or CD markers (which are easier to find - I recently found two brands in different places in my local Walmart).
Unfortunately, to my knowledge no one has done formal testing for this vulnerability; exactly how it happens, what conditions are prime for the damage to occur, etc. Everything is based on anecdotal experiences. However, I would encourage you to consider referring people to water-based permanent markers in the future. They're close to the same price as Sharpies, and the little bit of difference is worth the peace of mind to me.
Thank you for your time and consideration.
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is a longtime Mac user. He was using digital sensors on Apple II computers in the 1980's and has networked computers in his classroom since before the internet existed. In 2006 he was selected at the California Computer Using Educator's teacher of the year. His students have used NASA space probes and regularly participate in piloting new materials for NASA. He is the author of two books and numerous articles and scientific papers. He currently teaches astronomy and physics in California, where he lives with his twin sons, Jony and Ben.< And there's still a Mac G3 in his classroom which finds occasional use.
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