Add a small dollop of NC lacquer and thin with acetone. You want as little NC as you can get away with, because it is an insulator. Strip the ends of your wires, dip them in slurry, hang up to dry. After about an hour, dip them once more. Finish off with a dip in straight NC lacquer or PVC pipe cement. You can add a pinch of aluminum or fine Ti to the mix for sparks. (I don’t because a lot of what I do needs a very dark ignition to not interfere with the effect, but for most fireworks purposes a large ball of sparks would be desirable.) These pop easily on 9V and will go off reliably with as little as 4V but not on a single AA battery.