What can be used for impromptu EMF shielding?
To answer this question, yes, aluminum foil can be used as shielding. After all, many shielded cables use aluminum foil or aluminized mylar for exactly that purpose. However, aluminum oxidizes rather readily and its oxide is an insulator, so it can be difficult to maintain a good electrical connection to it. Screws with lockwashers can be effective.

However, in the comments on your previous question, we've pretty much ruled out EMI as the source of your problem anyway. You need to go back to that question if you want a quick solution.