Over the last 7 years, I’ve built up a DVD library of some 3,000 movies/TV series. Needless to say, I’ve learned some stuff about it in that time. One is that, while a DVD is an optical device and has a protective layer, it’s not indestructible. Although more resistant to wear and damage than, say, a vinyl record, the standard care for such a disc is still just as important. Handle it by the edges. Do not lay it flat on any hard or possibly abrasive surface. Do not stack. In other words, treat it like it’s crystal stemware. Irreplaceable. And some of them, being out of print, really are irreplaceable.
Now, first thing, if your DVD constantly hangs at the exact same point every time, but you don’t see a single scratch, hold the DVD at an angle where you can skim across the surface with your eyes. It’s like that there is the tiniest little dimple into the disc, like something poked it. There is no fix for that. The data area has already been damaged. Replace it while you can.
Cleaning, on the other hand, is not such a gentle, delicate issue. All of your standard DVD liquid cleaners are just 91% isopropyl alcohol. Available at any department/drug store for $1.50 a pint. I use a little 2-oz spritzer bottle (also available at the same stores for $1) to spray the surface. Don’t use rubbing alcohol, as it’s only 70%, which leaves streaks when it evaporates. Personally, I just use a paper towel for wiping the surface (gently). The alcohol does most of the work in dissolving the dirt, and the paper towel is mostly to pick up the dirt, not dry the disc. The evaporative properties of the alcohol does the drying. I’ve also never had a problem with the exact method of wiping, since I never scrub. They only tell you to wipe in a certain way in case you leave scratches from it; they’ll be less intrusive. Still have dirt left? Spray some more, wipe gently. Let the alcohol do its work, not the towel. What dirt isn’t picked up by the towel will flow off the disc (onto any absorbent material to protect your work surface.
Repairing scratches… Aye, there’s the rub, so to speak. Scratches, on its most basic, are not a problem in themselves. It’s only when a DVD consistently hangs at the same spot. Forget the toothpaste gimmick. I can tell you, after 5 years, it’s a load of crap. About the same time, I read where Pledge furniture polish was also effective. They even had a reason that I could buy. Since light passes through the protective surface, scratches tend to deflect that light and misread the data. Okay, makes sense. Same with minute scratches in furniture, looks dull. Pledge fills in those cracks, allowing light to pass through, and shine back with the original luster. Sounds good, may work for furniture, totally worthless for DVDs.
When basic cleaning doesn’t do the trick, there’s only one thing left; minimize or remove the scratches. Finally I broke down and bought a device called Disc Doctor (from Best Buy) for $50. It’s a motorized sanding wheel that turns the disc and strips a minute layer of the protective surface and turns off when completed. Often I have to only do one pass, and the problem is done. Sometimes it requires two passes. There have been a couple times when I actually needed to do 4 passes. The literature says that you can do up to 16 passes before risking damage to the data layer. Of course, if the scratch is deep enough to hit the data area, nothing will help recover the DVD. (Except for extremely expensive and proprietary software.)
So, given the high number of potentially scratched DVDs I deal with, buying such equipment is worthwhile to me. If you only have one or two that might have a problem, you’d find it cheaper to just take the disc to a DVD rental store and pay them a buck to do the same thing with their professional equipment. Same for CDs. And then care for them much more carefully in the future.