found some speaker wire of mine and wonder if it is still good. 12 gauge wire has gold tips on all ends except one. when i went to put new ends on i noticed that the wire was tarnished when i removed the plastic casing . upon further review as i look at the wire i noticed that the wire just looks dirty inside the clear plastic covering all the way through . when i cut the wire and look at the cross section it is nice and shinny so the only tarnish is on the outer part of the wire. i have seen wire that is oxidized even in the middle but this is not like that. will this slight tarnish effect the wire ? i was going to put some spades on and send to a friend who needs good wire but dont want to send him bad ones. any ideas??