Formvar : A gold colored insulating coating for copper wire used in Fender Strat pickups of the 1950's and 1960's (amongst others). This is the coating responsible for the favored sound of the legendary Stratocaster. Seems to have magic properties. If it's not wound with Formvar then it's not a authentic reissue. However Formvar is a low grade coating, really quite shitty compared to Polyurethane. It degrades over time causing the Aged effect.-----------------------