How Reliable is DVD Media ?

[Brian Ellis]

I agree that paper labels should not be used. The temperature of a DVD in a player can be quite high (~60 - 70°C in some cases). This may be enough to unstick the glue and I've heard of players being buggered up by bits of chewed up paper floating around. What I have noticed is that my Grundig player heats the discs up a lot more than my Philips one. Even so...

If I were you, I'd make a copy of your vinaigrette-treated discs, if they are important, in case they stop working. Polycarbonate is a funny plastic and you may possibly get stress cracking after a time after such a treatment. Just as a precaution.

[Debbie]

I quite agree about the risk in using paper lables. It happend to me some years ago with a CD sent to me by a friend.
Lables ? Never again!

As regards the temp. of DVD players I can say that this varies a great deal according to band. My Hitachi, produces the highest temperature of the lot. The Kiss much less and the H&B remains absolutly cold. The temp. will naturaly be transmitted to the media inside and will surly have an adverse effect on its performance.

Debbie

[Brian Ellis]

I wasn't thinking of the case temp, but the energy of the laser emissions that are used to read the discs. When you insert the disc, the system adjusts the level of laser energy to obtain max contrast between the 1s and 0s on that particular disc. With player/disc combinations that require high energy, the discs are heated more.

[Debbie]

Shure Brian; but I'm sure that the heating up of the player will in some way interfere with the media inside and also contrbute to an extent twards the lifting of any lables on the media.

Debbie

[Dr Mordrid]

DVD/CD labels lifting hasn't been a problem here in ages, not since Fellowes and others came out with their heat resistant labels. Fellowes model numbers;

Matte: #99942
Glossy: #84074

Balance is another issue, but with the newer application kits I've not seen a real problem there either. Older kits, yes. Newer kits by Memorex, Fellowes etc., no.

If you're still paranoid about this then either get printable discs and a CD/DVD printer or get one of the text-only thermal printers which work quite nicely. ~$80 at Office Max, but the ribbons are $30 each.

CD's are more susceptable to damage than DVD's because the recording layer is right under the label sides printing. Scratch it off and the CD is dead meat. DVD's differ in that the recording layer is fully embedded in the plastic.

In terms of heat:

DVD recordables phase change occurs at about 500-700 Celsius using a beam intensity of 8-15mw, but there are dialectric "heat sinks" on both sides of this region that conduct excess heat away in short order.

During RW erasures a 2-8 mw laser output is required, lowering the heat buildup even further.

During reads only a very small percentage of these intensities are used.

Because the W/RW laser pulse duration is so short (pit length is ~ 0.4 micrometer) little heat actually builds up, especially in comparison to that generated by the drive motor or leaking in from the rest of the computer.

It's certainly not enough to heat the disc to the level needed to affect the pits phase change, at least not for quality media.

Dr. Mordrid

[Debbie]

Thanks Doc,

Very informative indeed !

[Flying dutchman]

The labels that caused problems for me *were* Neato/Fellowes ones!

I had no problems with glue getting loose or labels peeling off, but rather with data becoming illegible near the outer rim of the dvds.
I assume the reason to be the following:
Paper is not an isotropic medium, the direction of the cellulose fibres isn't a completely random distribution due to the fabrication process of paper (the cellulose pulp gets squeezed between rotating steel rolls). So when the paper gets warm, it expands a little bit more in one direction than in the other. When you stick such a label on a DVD and it gets warm inside a player, the dvd deforms. But due to the anisotropic nature of the paper, this deformation isn't purely dish-shaped (what the laser optics could probably handle), it is rather wobbly. Near the outer rim the amplitude of the deformation is maximum and the laser pickup unit has problems keeping the laser focused on the fast-spinning disk.

Isotropic (tin foil) labels also exist, these are trouble-free for me so far. But they are much more expensive.