Yeah you can wax over Contact / Mylar .

Just be sure to use a wax with natural ingredients . Pure caranuba wax is best . The paste type - not the liquid . I wouldn't use any wax that contains strong solvents etc. on any playfield as there is no telling how it will react .

The polishing kits that Treasure Cove sell are also very good for bringing up dull contact / mylar to a nice glossy shine .