The Effects of Rubbed Metal on Electricity

A substance is a conductor or insulator, how tightly bound the electrons are to the nucleus. So for example if you charge the metal rod by rubbing it with a wool it's much easier for you to discharge the metal rod. A plastic rod is an insulator where it's a metal is a conductor so the insulator is much harder for the charge to be transferred. But in either way fundamentally the same thing is happening, you're building up charge by the rubbing action and it can be dispersed again by coming into contact with a neutral object of the opposite charge.