Tinned wire, copper wire, when immersed in tin after a period of time, why would ash and so on?
The reason why the color is black is usually caused by corrosion. The oxidation is usually slow. It may be that the flux is too acidic or of poor quality. Try "halogen free flux".
The copper wire must be washed before it is immersed in tin. Do you have any?.
Ash is oxidized, which is what happens when the temperature is high and the humidity is longer.
