1237be68dc54
tech



Hello Phil - 

--8<--cut 

MMC>> I use junked CDs as 'support washers' for mesh screening
MMC>> in various projects, and am amazed at how fast they age
MMC>> in weather and sunlight. First, in only a few weeks, the
MMC>> paint and coatings disintegrate and peel away, then
MMC>> minute striations begin to appear within the plastic
MMC>> itself. Within six months, there is no semblance of
MMC>> flexibity at all, and anything more than a medium 'touch'
MMC>> will shatter them. 

MMC>> My use of those CDs has no bearing on their intended use,
MMC>> but has provided me with a glimpse of 'grossly
MMC>> accelerated aging'. I would guess that many eight to ten
MMC>> year old CDs have had at least some exposure to sunlight,
MMC>> humidity, rough handling, spilled beverages, etc., and
MMC>> any in that age range probably should NOT be used in
MMC>> modern high speed drives. 

>> I never thought about that aspect of it, these things were
>> sold with the impression that they didn't wear out like
>> vinyl did. Hmm. I wonder how much of what I have on hand
>> here is that old? Probably not much, as I came to these
>> things rather late, and the first drives available when I
>> got mine were 4x... 

PM> My thought exactly. You mean after all that trouble
PM> assembling what I've been thinking of as my final and
PM> permanent jazz collection, it's gonna spring a spider's web
PM> of cracks and then crumble to dust? Sheesh. 

I had mentioned this aging process quite some time ago for ALL
plastics and everyone (then) insisted I was wrong. 

One of my former employers specialization was plastics
engineering. He told me that all plastic continually shrinks
although at a much decelerated rate after the first few weeks
and will return to various carbon compounds and crumble. As I
remember it he mentioned 10-15 years. I have managed to keep
various plastic objects for that long and they do crumble if
you try to disassemble them. 

I don't think sunlight is a factor but heat definitely is a
catalyst. 

>
>        ,                          ,
>      o/      Charles.Angelich      \o       ,
>       __o/
>     / >          USA, MI           < \   __\__
 

___ * ATP/16bit 2.31 * 
... DOS the Ghost in the Machine! http://www.undercoverdesign.com/dosghost/

--- Maximus/2 3.01