The invention relates to a wire (1) which comprises a copper or pinchbeck core (2) surrounded by a pinchbeck coating consisting of a continuous pinchbeck sub-layer (3) in phase β and a superficial layer (4) with a fractured pinchbeck structure in phase ? enabling the appearance of pinchbeck in phase β in the fractures (5a). In this way, the electrical discharge machining speed is essentially increased.