Re: Delphi version control

From: John E. Doe (nobodyyouknow_at_dontneedspam.com)
Date: 12/29/04 

Date: Wed, 29 Dec 2004 15:56:58 -0500

On 29 Dec 2004 15:34:34 GMT, vbdis@aol.com (VBDis) wrote:

> When the pits are burnt into a CD-R, cannot there exist fringes at the borders,
> that could drop or flow down?

There's no evidence to support this...and I've neither heard nor read
of any such cases.

>I don't see how a vertical storage will prevent bending, as opposed to
>horizontal storage. Placed horizontally on a flat surface, or in a stack, there
>is no way the gravity could bend a disc.

Very true, but people don't place discs on a flat surface. They store
them in their jewel cases, and as such, the CD isn't sitting flat.
It's being supported from the center ring only, and the majority of
the surface is "floating" in air, and thereby subjected to gravity.

>Okay, sounds reasonable. But why 4 C? Is that only a convenient frigerator
>temparature, or has it to do with the extension of water, that consumes the
>most space at that temparature?

I used 4 degrees in my posts because that's the low-end of the
recommended storage temperature that most CD manufacturers state. And
as a happy coincidence, it also happens to be the temperature used in
most refrigerators.

I wouldn't recommend going lower than 4 degrees because then you get
too close to the freezing point, in which case you're far more likely
to damage the disc. Going below freezing is definitely not a good
idea for several reasons, the most obvious being that you could end up
cracking the disc...not to mention the stresses to the material
associated with having to pass from one thermal layer to another.

>What will happen when the disc later is warmed up to working temparature,
>perhaps more than once?

As long as the media doesn't have to cross the freezing point
threshold, then it shouldn't be a problem. It's much easier on the
material to bring it from 4 degrees to 20 degrees than it would be to
bring it from -10 to +20.

But in an ideal case, you wouldn't want to subject the disc to
temperature changes anyway. The idea is to keep a permanent copy in a
safe, long-term capacity. Once you have the media in your ideal
storage environment, you would want to leave it there until such time
as it was absolutely necessary to use it again. And in the meantime,
you could work from other copies that you store at normal room
temperature.

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