I didn’t think that LCD’s do this, but they do. I spent about six hours last night burning DVD-Rs on my iMac, and another six or seven hours this morning and afternoon. During that time, the monitor image was static, with the Disk Utility (Apple’s built-in disk repair and formatting app) window dominating the screen. I could swear that I’ve done stuff like that in the past, and never had an issue. I have come back from a day out to discover that the monitor was left on with a static image. And yet, never had burn-in–until today.

I was viewing an image afterwards, and noticed lines where there shouldn’t have been. Then I noticed more stuff, lines of text and so forth, and eventually saw that it was the image of the Disk Utility window. At first, it was hard to figure out: CRT phosphor burn-in is most visible on white, but LCD burn-in shows up not at all on white; you need some shading to see it. Figuring that inactivity would be, if not the best thing, then perhaps the least harmful, I turned the machine off for several hours.

For a while there, I was pretty upset; this is a 24-inch iMac, the screen is kind of hard to ignore. To have permanent burn-in would be a huge pain in the neck. Now, I do have Apple Care on this, but (a) I was concerned that Apple would see this as user-inflicted damage, and (2) it would mean the computer would probably be gone for quite some time whether or not it was covered under warranty. Plus, to have the screen burn an image like that with relatively little exposure was not a good sign for the future.

Fortunately, a bit of research revealed that this was not as bad as I had feared: while CRT phosphor burn-in is permanent (as evidenced by the volume indicator on the TV that’s getting replaced in a few days), LCD screen burn-in is temporary. My initial instinct of turning off the monitor was the correct one: letting the “tired” monitor rest for hours or days (depending on the extent of the damage) will allow the burn-in to dissipate. Apparently I can expect it to completely disappear in a short while. Whew.