Alumina is the protective coating that covers aluminum when exposed to oxygen. It's actually corroded aluminum that prevents the aluminum from continuously corroding.What I didn't know until recently was that alumina is an electrical insulator. If that's the case why then isn't aluminum an insulator if one is trying to pass current along its surface?
Corroded aluminum is not the same substance as rust is not the same as iron. Iron is simply Fe, rust is Fe2O3 if I am correct. So the alumina is not the same as aluminum. Just because something has an element in it doesn't mean it has the properties of the material, or is even similar to that element in anyway. Glass is conductive when its molten, but not when its cool and hard, like windows. So unless what you are dealing with is exactly the same thing, you can't assume anything about it, generally. EDIT: Aluminum is Al, alumina is Al2O3. Alumina is an oxide, aluminum is a pure element, they aren't the same so they can have different properties. As for being an insulator, the layer of alumina is usually so thin it only adds a small amount of resistance to a circuit. If you had a block made of pure alumina and you tried to run current through it it would add lots of resistance or so much there would be virtually no flow.
Aluminum is an efficient conductor of electricity. A usual fabric that is not conductive is glass but glass will habits heat. Wood isn't warmth conductive or an electricity conductor however has a low combustion factor. You probably have a specific utility you are watching for then you definitely'd better ask extra certain questions.
