Restoring Apple IIs, others...

[labelas@hotmail.com (Labelas Enoreth)]

Yeah, perhaps this is a silly question, but I find it very satisfying to
find a piece of dirty, discarded, unappreciated old computer equipment and
make it all clean and new looking...it just seems nice to watch all the
grime and dust get washed away and have a nice computer on your
hands...however, I have a lot of stuff which was done in platinum-gray
plastic which has yellowed noticably...now  in many cases, I am almost
certain that it is not from dirt, smoke, or sunlight...it just seems
to...happen. Does anyone know of an effective way to...um...bleach the
gray plastic back, or is it irreversible?

Things that have fallen prey to this yellowing...
A IIgs with 3.5 drive and AppleColor RGB. about 4 Platinum 5.25s. My SNES.
Some of my Mac equipment. Some other stuff. Any ideas?