February 02, 2007

Have you been protecting the wrong side of your CDs?

Most people protect the play side of their discs (the "bottom") and don't think about the label side at all.

Big mistake.

The protective layer of plastic is actually thinner on the label side than on the bottom. Click here for a handy-dandy cutaway drawing. One quick glance will explain what the heck I'm trying to say. It's OK, I'll wait...

See what I mean?

Just below the thin protective layer on top of your disc is the precious dye layer. The dye layer is where your data is stored. Scratch the top, and you've got a serious problem. If you puncture the data layer you will cause irreversible damage to your disc.

Practical Tips for CD Care

1. Make multiple copies. Digital copies are cheap! Take advantage of this fact and burn a second set of CDs. Ask a relative to store them away from your other copies. This will protect your data from catastrophic events such as fire, flood, etc. You can also store additional backup copies on a remote server. The more copies there are, the more likely any given image will survive.

2. Protect the top and bottom from scratches. That means storing CDs in jewel cases with a central hub. Avoid storing important CDs in a sleeve or envelope because every time you remove or return it, you risk scratches.

3. Never write on the top of a CD with a regular pen. This can also cause scratching. The safest way to label a CD is to write with a felt-tipped marker on the round space in the center of the disc. There's not a lot of room in this area, so I recommend you number your CDs and record that number on the CD itself. The paper insert in your CD case can include detailed descriptions of what's recorded there.

4. Never touch the surface of a CD. Gloves are a great idea, too. The oils on your fingers and hands contain salts and acids that are not good for CDs. If you absolutely can't stand to wear gloves, be sure your hands are clean and free of lotion. See the photo above for an example of proper handling. Edges only, OK?

5. Store your CDs away from light, heat, and dust. All of these factors can cause damage. A box with a lid is a great option.

6. Leave unused CDs shrink-wrapped until you are ready to record one. This is more important for the CDs you consider your digital archive, not as important if you're just burning a playlist to share with a friend.


Rod said...

This reminded be of way back about 1985 when CDs were new. The were demonstrating how you could rough up the surface and the disc would still play. I ran my thumbnail across the back and killed the disc. :-)

Sally J. said...

Rod, thanks for sharing your clever, funny story. I hope the person giving the demo wasn't withing strangling distance when you pulled that one.

I also heard from someone who accidentally got a shipping label attached to the top of a cd. When she tore it off, the cd was completely destroyed.


jean said...

If you use labels, cover them over with new ones, DON'T peal them off. The data layer pulls right off.
I found some CD labels (the kind that cover the whole disc) from the computer/printer section of the store.
Now, if I re-use a disc or the label side starts looking too cluttered, I just cover the whole thing.

Sally J. said...


Just so you know...sticky paper labels have a slight chance of making the cd uneven. Which means it won't spin correctly. Which means it can't be read.

For everyday stuff I wouldn't worry about it. But if we're talking about the only backup of your family photos? Write on the inside hub with a permanent marker.