Tommy,
If you are hanging a skillet from the handle, I cannot see how a bubble would form. The gas that is formed at the cathode is hydrogen, and would not cause corrosion. It looks like the black stuff is ferrous iron. Ferrous iron rubs off under running water. The red rust is a mixture of different iron oxides, but the ferric oxidation state is what gives the red color. Since you had the pan in the electro system for a while, the red rust may have been converted to the black, ferrous form, and that is what you are seeing. I suspect that the black ferrous iron oxide will be removed as you clean the pan.
In theory, you can leave a pan in the electrolyte solution with the charger attached to the anode and cathode and nothing will happen. The diodes in the charger should prevent current from flowing the wrong way. As a precaution, I disconnect the charger from the pan when the charger is not running. You can also leave a pan in the electrolyte solution and not have rust form as long as the pH of your solution is sufficiently alkaline (the pH is around 10). If you used either sodium carbonate or sodium hydroxide to make the electrolyte solution, the pH will be high enough to make the pan "passive" meaning that the iron will not participate in oxidation/reduction reactions. I wrote an article for the newsletter that went into detail on this topic.
As far as putting copper wiring, or other metals that are not sufficiently corrosion resistant, into the electrolyte solution, they are also made passive by the high pH. The problem happens when you use copper to connect the anode to the charger (the positive connection) and the current is flowing. With the current flowing, the high pH is not enough to prevent electrons from being stripped out of the metal, and the metal corrodes. You can safely use copper and other metals on the piece you are cleaning (the cathode).
One final thought - it is important to have a piece of cookware fully submerged in the solution. A line will develop at the interface between the solution and the air that is about impossible to remove.
Hope this helps.
Jeff
