Yellow cases.. can they be made white again?

[shIva]

Is it possible to clean a yellow case with JIF or something to make it white again?

i used special foam cleaner for plastic to "unyellow" a keyboard. it worked really good :-)

i used "KONTAKT CHEMIE" and "DATA FLASH - FOAM CLEANER"

just spray it on the parts you want to clean, go and have a cigarette ( or anything else which takes 5 mins ;-) ), get the foam off the parts - finished

[shIva]

this is the "DATA FLASH - FOAM CLEANER"
there´s nothing written about the ingredients on the label. just some warnings about handling/using and that it is extremely flammable.

the foam cleaner smells similar to oven cleaner spray for the kitchen, perhaps it´s the same (tho i haven´t tested it yet)
it could be worth a try to look for foam cleaner in electronic shops (there i got mine, too)