the scratchplate on my squire strat which was white before has now turned almost a darker shade of cream than the body. Although I like the old, battered look on strats, how can a make the scratchplate look a little white (but not totally birght white)
take it off and clean it
You could try a 10% bleach 90% water mixture on a soft cloth. If that plastic has fire retardants in it, that would explain the color change. Over time, fire retardant plastics turn a creme color, that's why old NES systems and computers turn that color as well.
Fire retardants in case you're shredding too hard?
Seems weird to put fire retardant plastic on an instrument made of wood though... :/
Most modern plastics are fire retardant.