On Jun 24, 12:07*pm, msg wrote:


I would appreciate a discussion on what environmental factors
cause *white plastic equipment cases... to yellow

There are two or three causes. Firstly, UV light can
cause 'color centers' to form, kind of like the purple tint
that develops in desert glass. Secondly, polymers
are developed from unstable (monomer) ingredients,
and there are complex aging characteristics, which
cause the plastics to shrink, embrittle, or change color.

Dirt, also, may bond to the surface; if normal household
cleaners (soap, Windex, Formula 409 etc.) don't work,
it might be useful to apply a mild abrasive (toothpaste
or metal polish).

Unusual cleaners including waterless hand cleaner,
denatured alcohol (for fingerprints on keyboards), dilute
lye (for smokestains), vinegar (for some mineral dusts)
have proven effective. Isopropyl alcohol is NOT
recommended for translucent or transparent plastics.