Re: Monitor Burn-in / plastic yellowing

["Michael J. Mahon" <mjmahon@aol.com>]

jsnospam@cimmeri.com wrote:
> Mitchell Spector wrote:
>
> >    About a decade back I found a brand new condition memory expandable
> > Apple IIc, perfectly white. I set it up on a desk in room that was sunny (not
> > even direct sunlight) and after about two years the plastic changed
> > to a yellowish hue.
>
>
> I don't understand how indirectly lighting (with no UV content) would
> cause yellowing?   Isn't it the UV causing the plasticizers to
> destabilize?

We need some better experiments to determine just what wavelengths
are responsible for yellowing, and which for bleaching.

It would also be necessary to allow for differences in the plastic
case materials, since not all of them are made in exactly the same
way, or with the same pigments.

With what we have heard so far, it would seem that long-wave
UV (>300nm) produces yellowing, while short-wave UV (<300nm)
bleaches the plastic, at least of //c's.

Glass is an effective filter of short-wave UV, which is why
it's hard to get sunburned inside, even sitting in the sun.

Most Apples spend their days inside, and so get more long-wave
UV than short-wave UV.

-michael

Parallel computing for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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