It struck me the other day that I carry thirty or forty CDs and about ten DVDs around in my car in Southern California, where the internal temperature of a parked car can reach 120 degrees in the summer. I once parked in Arizona and had left a thermometer on the dash. It reached 160 degrees.

But my CDs never warp.

If I remember right, Laser Discs used to have a mark, or sticker, that said "Heat Kills," which makes sense to anyone old enough to remember the fine sculpture that is created when leaving a phonograph record in the car.

How come my CDs are not toast, or at least nicely textured?

"It's life Jim, but not as we know it."

LDs are different from CDs and DVDs. LDs are glued together and heat does kill glue. CD/DVD is pretty much all plastic and metal and is essentially welded together with more plastic. They are quite heat resistant. You may need to be more careful with recordable CDs and DVDs since they have more ingredients, I'm not sure.

That said, there is some point when direct sunlight can probably destroy a CD, use a little caution.

I think the problem these days is mainly with CDRWs, the dye used to record data can actually be erased by heat and/or direct sunlight.

I've noticed that with my CDRs. When they get hot, the sound is degraded and gets very scratchy. When they cool down, they sound fine. I don't have this problem with "factory" discs.

I boot leg a ton of shows (Dead, String Cheese Incident, Keller Williams....lots of jam bands) and Mitsui and Klone are the best discs I have ever used, and the best place to get them from what research I have done is American Digital ( www.am-dig.com ) . Below is the techy info on the difference in the discs in regards to heat and light.

Organic Dyes Used on CD-Rs

MAM's Patented Phthalocyanine

All CD-R discs incorporate a photosensitive dye layer where your data is stored--it's what gets "burned" when you write to the disc. This layer is where your data or music is stored in the form

of "pits" which are oblong areas that are discolored by the writer. These pits are read by the player and ultimately transformed into the "1s" and "0s" that make up your digital information (music and data look the same to the reader). The accuracy of the stored information is directly affected by how this dye reacts. That's why the dye is so important.




Sample of CD "Pits"

MAM's Patented Phthalocyanine (tha-lo-cy-a-neen) dye has several advantages over others:

1. More responsive to the writing laser so cleaner, better defined pits are created
2. Longest lifetime of any photosensitive dye
3. More transparent, contributing to MAM's high reflectivity

What does this mean for you? Cleaner pits means fewer errors. Higher reflectivity means better compatibility among readers. Longer life......300 years is, for all intents and purposes, forever. (estimated lifetime is 300 years for our gold CD-R and 100 years for our silver)

The Phthalocyanine Molecule

Contrary to the two other types of dye with linear molecular structure, Phthalocyanine has an annular structure, thus offering the benefit of solidity by forming a strong and extremely stable chemical bond.

MAM invented Phthalocyanine and has a world patent on the substance.


How does MAM dye compare?



This chart shows the number of errors that develop after exposure to high humidity and high heat.

(The discs are put into an environmental chamber at 80 C° degrees and 85% relative humidity. Industry standard analysis techniques can relate these tests to real life).




Other Organic Dyes


Cyanine

Those CD-Rs are green, and include an organic dye based on Cyanine. Their quality is variable, and they have a shorter lifespan than CD-Rs using Phthalocyanine-based dye. Light reflection is lower, given the color of the dye, and the burning is less accurate.


Metal Azo


The CD-Rs made with metal azo are blue, and use a silver reflective layer, which gives good reflectivity despite the color of the organic dye. Like Cyanine, the dye is less stable than the Phthalocyanine, has a higher BLER rate when recording, and consequently a shorter lifespan.